and the ova, notwithstanding all the tales of the earlier naturalists to the contrary, are not made prolific until after their expulsion from the female. In their passage from the ovary they receive a coating of a gelatinous fluid secreted by a peculiar gland, and insoluble in water, but which swells out greatly after the deposition of the eggs. These are always clustered, and the pattern of the cluster varies in the different families in the Sepia it resembles very exactly a bunch of black grapes, both as to size and colour;* in the Octopus they are irregularly heaped in bunches attached to algæ; and in the Loligo, or Calamary, they are imbedded in a regular series of cells in a pudding-like gelatinous intestine, from eight to twelve inches in length, many of them being united together by a ligament in a common centre, so that the cluster, when mature and entire, may be compared to a woollen mop. At first the contents of the egg are colourless and fluid, and apparently homogeneous; but shortly after their impregnation, a speck becomes visible in the centre, and the young foetus, drawing nourishment from the yolk through its slender cord, grows apace, and has assumed a recognisable form before the yolk is consumed, and before it is ready to burst through the thin membranes which contain and protect it. It is probable that the female brings forth once only during the year, but the number of eggs laid is very considerable. Bohadtch has calculated that from a cluster of the common Loligo, of the average size, there are not fewer than 39,760 young ones produced.‡The males, if we are to credit ancient story, are very constant husbands, accompanying their females everywhere;' and they have their attentive care very ill requited. "The males of the cuttles kind," says Pliny, "are spotted with sundry colors more dark and blackish, yea, and more firme and steady than the female. If the female be smitten with a trout-speare, or such like three-forked weapon, they wil come to aid and succor her: but she again is not so kind to them, for if the male be stricken she will not stand to it, but runs away."

* Boys in Lin. Trans. v. 231. There is a figure of a cluster in Rondelet Hist. des Poissons, i. 368.

+ Dr. Coldstream has given a minute description of the eggs of Sepia officinalis in Proc. Zool. Soc. Lond. i. 86, an. 1833. See also Cuvier in Ann. des Sc. Nat. xxvi. 69.

De Anim. Marin. 161. Tab. xii. of this work contains a tolerably good figure of the clustered ovigerous mass. See another in Cyclop. Anat. and Physiology, i. 559. fig. 241.

III. HERMAPHRODITICAL MOLLUSCA.

It is a common remark that the most improbable fictions of the novelist meet their counterparts in the romance of real life; and it may be said with at least equal truth, that the wild creations of the poet find themselves realized among the structures of organised beings. Invention has not gone beyond what is actuated. Men who carried their heads under the shoulder are not more eccentric than the creatures which carry their legs and arms on their head; and we can instance whole tribes of animals rivalling the nations which were feigned to have their mouths in the breast. When the poet sang the metamorphosis of Hermaphroditus and Salmacis, and incorporated them in one, he imaged a monster which finds indeed no parallel in higher organisms; but amongst the Mollusks there are hundreds which, if known to him, might have suggested and almost justified the fancy. "Beyond those Nasamones," says Pliny," and their neighbours confining upon them (the Machlyes) there be found ordinarily Hermaphrodites, called Androgyni, of a double nature, and resembling both sexes, male and female, who have carnal knowledge one of another interchangeably by turns, as Calliphanes reports."* An exact description this of some tribes of mollusks which border on the dioecious Gasteropods. John Ray discovered, in the gardens of Cambridge, that the common snail was of the nation of the Androgyni,-male and female, every individual having the peculiar organs of both sexes. Subsequent researches have shown that this structural union prevails, with a very few exceptions, in all the land and fresh-water snails which breathe the air uncombined, in all the nudibranchial Gasteropods, in the Inferobranches and Tectibranches, and in the Pteropods, together constituting a very considerable section of the Mollusca. But although really bisexual, it is also true that no individual of these many tribes can impregnate itself; the union of at least two individuals is necessary for the propagation of the species: and it is asserted that though either of the two can act the part of the male or of the female, yet that one of them only is made pregnant from one union. I have said that at least two individuals are required to unite, and you may notice with surprise the limitation, and probably deem the phrase a mere pleonasm, but it is not so. In the lacustrine pulmonated Mollusca, represented by the Limneus and Planorbis,

Holland's Plinic, i. 154.

the disposition of the sexual organs is such that the animal cannot not only fecundate itself, but even "mutual impregnation between two individuals is impossible. To complete the purpose of nature, the animals require to arrange themselves in lines or chains in a certain position, so that the sexual organs may be in contact, one with the male organ in connection with the oviduct of the nearest adjacent animal on one side, and its own oviduct in a position to be impregnated by a third individual. In the ditches where they abound may often be seen long chains of these animals, in which, with the exception of the two at the extremities, all are alternately fecundated or fecundating.'

When amorous poets sing of Cupid, his quiver and his darts, they use a language which some grave naturalists have believed may be applied literally to describe the loves of some of our commonest snails (Helix aspersa, hortensis, arbustorum). The season urges them to unite, and the wooing pair make their approaches by discharging at intervals several small darts at each other. These darts are shaped something like a bayonet, and made of a horny crystalline substance; they are contained within a cavity-the quiver on the right side of the neck, from which they are said to be launched when the animals are about two inches distant from each other; and the darts being shot home, the affections are won and a marriage is the result! Such is the story you will find told in almost every popular compilation of natural history, with more or less detail of time and circumstance, sometimes in prose and sometimes in verse; but it has little foundation in fact. The existence of the darts, in some few species of Helix, is certain; while the power of the snail to throw them from its reservoir is imaginary.†

Brewster's Journ. of Science, Oct. 1829, p. 336; Ann. des Sc. Nat. xxx. 59. Adanson Hist. Nat. du Senégal, Coquill. p. 10.; De Montford Conch. Syst. ii, 264 and 272.-To those curious physiologists who will have a reason for every thing, the following passage, containing a reason for the hermaphroditism of snails, may be acceptable :-" Hujus autem divisionis illa, ut opinor, præcipua ratio est: nempè, cùm id genus animalia onnino pedibus careant, sine quibus nullam esse posse copulam, invita fœmina ad venerem peragendam ; itaque ut ambo sint mares, ex aliqua saltem corporis parte, necesse est. Etenim in coitu celebrando solicitatæ fœminæ ferè mares metuunt, et aversantur: ideoque et unguibus et dentibus pleraque animalia fœminas, dum eas subigere cupiunt, sibi arripiunt, omnibusque viribus detinent. Igitur in Cochleis, quibus nec ungues, nec dentes, idonei sunt, ne fœminarum protervitas coitui obstaret, ambo maris œstri participes facti sunt, quò ad copulam jungendam eodem impetu sibi mutuò adcurrant, ineantque."-LISTER, Exer. Anat. de Coch. 145.

"If such are ever discharged at each other we have been extremely unfortunate in our observations, for in no one instance could we ever find the

My own observation agrees with what Bradley tells us of these amatorculists: The manner of their meeting to couple is well worth observing; in dewy evenings, or after a shower of rain, they crawl upon the grass in a circular manner, making several rounds, till they come near enough to one another to hit their design: I have observed them sometimes make above twenty turns before they could join."* After the union has been dissolved, you may frequently find the dart sticking in the neck of the snails, or merely adhering to the skin by the tenacity of its mucus, for the penetration of the point is very slight; nor do I know what the true use of the dart is, being little pleased with the conjectures that have been offered.

The spawn of the aquatic tribes, whether of the fresh waters or of the sea, is a gelatinous mass, in which the ova are imbedded in a manner similar to that of the Littorina vulgaris. The jelly seems to have some peculiar qualities, -to be a substance intermediate between albumen and gela

dart penetrated; though at the time the animals are close the point may irritate; but it is neither sufficiently strong nor sharp-pointed to penetrate the tough skin with which these animals are furnished."-MONTAGU, Test. Brit. 410. See also Müller Verm. Fluv. and Ter. ii. pref. xiii., and Draparnaud's Hist. des Mollusq. p. 6, 7.— Blumenbach has figured the dart of the common snail in his Elem. Nat. Hist. trans. pl. 1. fig. 8; and Lister more accurately in the anatomical plate ii. of his Hist. Conchyliorum.

*Phil. Account, p. 127.-The manner of courtship is, however, often less formal; and few can have leisure or patience to watch their tardy advances. I need only refer to Swammerdam's account of them.

+ Baker has given a description of the spawn of Limneus putris, which is good enough to be quoted:" The spawn, when first deposited, appears to the naked eye like a transparent jelly; but if examined by the microscope one sees in it numbers of small and exceedingly pellucid oval bodies, at little distances from one another, inveloped in a gelatinous substance; having each of them towards one of its extremities a very minute dark speck, wherein, if carefully examined by the greatest magnifier, a pulsation may be discerned. This speck will be found to grow larger from day to day and to become a perfect snail, with its shell complete, several days before it bursts through its integuments. When the eggs are about a week old the embryo snail may be discerned in its true shape, turning itself very frequently within the fine fluid in which it lies; and the heart is then a most agreeable and amazing spectacle, shewing itself very distinctly and resembling a little oblong bladder, much less at one end than the other: the pulsation proceeds under the eye with great exactness and regularity, and the systole and the diastole of this vessel are nearly equal to those of the human heart, somewhat more than sixty pulsations being performed in a minute, as I have found by several trials, keeping my finger at the same time on my own pulse, which usually beats one or three strokes more. The heart is large in proportion and may be always seen, until the animal increasing in bulk and becoming consequently more opaque, in some positions it hardly can be perceived; but as the animal frequently turns itself within

tine, distinguished from the latter by its insolubility in water, and by affording no precipitate with solutions containing tannin; and from the former by not coagulating on the application of acids or electricity, and by forming compounds with the alkalies which are not saponaceous. It is sufficiently tenacious to adhere with firmness to the leaves and stones on which it is deposited, and compact enough to retain its form. This is usually oval or linear-oblong, but sometimes the figures are more artificial. Messrs. Alder and Hancock have figured the spawn of many Nudibranches, which is often laid in coils, modified in character in different species. You have here the representation (Fig. 76) of a

the egg a little patience will bring the heart in full view again, and that as long as the embryo continues within the egg. Nay, even after it is hatched, the heart may be discovered for some days through the transparent shell."Employm. for the Microscope, p. 325, 326.

The eggs of the Ampullaria, an exotic genus of fresh water shells, are in the form of little rounded vesicles, often agreeably coloured with green and clustered in groups upon the stalks of aquatic plants. RANG, Man. 195. See the Ray Rep. on Zoology, 1845, p. 120, for a description of the egg capsules of Valvata piscinalis."