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Return of the Prince Edward County Mutual Fire Insurance Company, for the year ended thirty-first of May, 1872. (Not printed.)

PRELIMINARY REPORT

ON

DREDGINGS IN LAKE ONTARIO.

Hon. ADAM CROOKS, Q.C., M.P.P.,

Treasurer of the Province of Ontario.

SIR, I have the honour to submit herewith a preliminary report on the dredgings carried out, on behalf of the Government, in Lake Ontario, during June and the early part of July.

The present report is merely preliminary to a more extended report, in which a detailed description will be given of the animals obtained in these dredgings. This extended report I hope to be able to present to you in the course of two or three months. I have the honour to remain,

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The dredgings to which the present report refers were all carried out in the month of June and in the early part of July, and were made partly from the yacht "Ina," and partly from the steamer " Bouquet. They were carried on entirely by hand, and the dredges and rope employed were such as are ordinarily used in deep sea-dredgings. In dredging in deep water, however, a bag of embroidery canvas was attached outside the ordinary net-an addition rendered necessary by the extremely fine nature of the mud at great depths. Even with this precaution, the dredge not unfrequently came up empty from great depths, or with all of its finer and more delicate contents more or less completely washed out. In deep water, also, a fifty-six-pound weight was attached to the

rope, at a distance of about twelve feet above the dredge, and the same was necessary in the shallower water, where the weeds were very thick, in order to secure that the dredge should reach the actual bottom.

The dredgings were all carried on within a radius of ten miles from Toronto, and the following will show the nature of the bottom at different depths, and the chief localities at which the dredgings were prosecuted. As, however, the results obtained were very uniform for the same depths at different places, it will be sufficient to draw attention to a series of the more characteristic and important hauls.

In Toronto Bay itself, numerous hauls were made, both from the yacht and the steamer, and the bottom proved very varied, though the depth is almost constantly from two to three fathoms. The greater portion of the Bay, comprising the central portion of its area, has a bottom which appears to consist uniformly of a tenacious, exceedingly fine, clayey mud, the colour of which is a greyish-blue, whilst its temperature is comparatively low. All the shells in this clay are dead; but it contains numerous small annelides of the genera Suenuris and Chirodrillus, along with many larvæ of a dipterous insect allied to Chironomus or Corethra, the latter being very conspicuous from their brilliant red colour. The muddy bottom appears to be almost or entirely destitute of any growth of weeds, and does not seem to encroach upon depths of less than two fathoms.

Towards the edges of the Bay, where the depth diminishes to one fathom and a-half, or less, the bottom is covered over considerable areas by a dense growth of weeds of different kinds. The chief varieties of bottom in this shallow zone are the following:-Pure siliceous sand, with dead shells, almost or quite destitute of life. 2. Sandy mud, with a dense growth of Charae, containing numerous Gammari, small leeches, larvæ of Chironomus and Ephemerids, with shells of Lenio, Cyclas, Paludina, Planorbis, Valvala, Melania, Pisidium, and Physa. 3. Sandy mud, with the debris of plants, and sometimes with peaty layers, supporting a luxuriant vegetation of Anucharis Canadensis and Charae. The life in these portions of the Bay consisted of much the same animals as the preceding, except that the Gammari were absent, unless in the occasional patches of Charas brought up by the dredge. In some places, in from one to one and a-half fathoms of water, the sand was crowded with fresh-water Mussels (Leniones), the dredge coming up completely packed with living and dead shells. This was especially the case at several points under the lee of the "Island," a long, flat, insulated strip of land, which forms the southern boundary of the Bay, running parallel with the lake-shore, at a distance of about a mile and a-half from it, to a mile and three-quarters.

Another series of dredgings was carried on from a point in the open lake about eight miles to the south of Toronto, on a line extending to the Toronto Rolling-Mills, the depth varying from forty fathoms at the southern end of the line to three fathoms at its northern extremity. The deepest dredgings along this line were only partially successful, the dredge bringing up nothing but good.sized pebbles, all the finer materials having been washed out before it reached the surface. In about fifteen fathoms, the bottom was found to consist of a tenacious blue clay, distinctly laminated, and containing numerous broken-up stems of plants, along with small pebbles. No traces of life could be detected beyond a few small annelides of the genus Saenuris. Another haul in ten fathoms brought up the dredge full of sand and pebbles, with no traces of life; and another, in eight fathoms, showed a bottom of clear sand, with dead shells of Cyclas and Pisidium, but devoid of al vestiges of animal or vegetable life.

Another series of dredgings was taken along a line extending in a south-west direction from Toronto Point to a point about five miles out in the Lake, the depth varying from eight to fifteen fathoms. In this case, the bottom was found to consist uniformly of an exceedingly fine, bluish-grey, clayey mud, with numerous patches of a small bushy Alga (a species of Cladophora). The mud contained very numerous minute annelides of the genus Saenuris, along with dead shells of Cyclas, Pisidium and Planobris; and the bunches of Cladophora yielded a large number of little Ostracode Crustaceans, and a few beautiful little Amphipods, which are as yet undetermined.

Another series of dredgings was carried out still further to the south-west of the ground examined in the series just mentioned, at a distance of about eight miles from the shore. The depth here varies from thirty to forty-five or fifty fathoms; and the bottom was found to consist uniformly of a fine greyish mud, sometimes highly argillaceous,

sometimes more or less arenaceous, with many minute pebbles disseminated through it, and containing a few dead shells of Planorbis and Pisidium, and much broken-down vegetable debris. Every haul also brought up numerous specimens of a beautiful flesh-coloured Amphipodoris Crustacean, and a few minute annelides; but no other traces of life were obtained. The Amphipods are apparently referable to Pontoporeia, and are apparently undistinguishable from the Pontopreia affinis of the Swedish Lakes; but they will be treated of at greater length hereafter.

Another series of dredgings were taken in Humber Bay, about four miles to the west of Toronto. Here the bottom, except near to the shore, consisted of a tenacious bluishgrey clay, sometimes with reddish patches in it. Vegetable life was very scanty; and animal life consisted entirely of many minute Annelides.

Lastly, an examination was made, partly with the dredge, and partly by means of a hand-net, of the shallow water in the immediate neighbourhood of the "Island," and of the extensive ponds which communicate with the Lake. The bottom here consisted, for the most part, of a black mud, composed almost entirely of decayed vegetable matter, and supporting a dense growth of Vallisneria, Anacharis, Pontederia, Chara, Nymphaea, and Nuphar. Animal life was naturally extremely abundant, comprising numerous examples of Limnaea, Physa, Planorbis, Paludina, Cyclas, Pisidium, and Anodon, along with two species of Gammarus, and many small Ostracode Crustaceans, a few leeches (Clepsine), very many large scarlet water-mites (Limnoschares), numerous aquatic insects (Nepa Gyrinus, Dytiscus, and larvæ of Chironomus, Libellula, &c.), and a large number of young fishes Pimelodus, Perea, &c). Numerous Terrapins were also observed, and a single specimen of Menobranchus, but the latter, unfortunately, was not secured.

In the following list are indicated the chief forms of animal life which were obtained in these dredgings. Time has as yet not permitted of many specific determinations being made; but the species will be described at length in the extended report, which is in process of preparation.

LIST OF ANIMALS DREDGED IN LAKE ONTARIO.

ANNELIDA.

1. NEPHELIS, SP.

A small leech, nearly an inch in length when at rest, with an oblique posterior sucker, and of a liver-brown colour in life. Nearly allied to if not identical with N. Lateralis, Say.

Rare in three fathoms, Toronto Bay.

2. NEPHELIS, SP.

An exceedingly remarkable form, which is entirely new to science. The habits of this little leech are very remarkable. The adult usually places itself with its entire ventral surface closely pressed to some foreign body, such as a stone or dead shell, to which it adheres like a small limpet or a Chiton. When forcibly detached or irritated, it rolls up like a hedgehog, or like a myriapod of the genus Glomeris. The objects served by these habits, so peculiar amongst the leeches, become obvious when it is seen that almost every individual carries attached to the ventral surface of the body a large number (from twenty to thirty) of small leeches. The young are attached to the ventral surface of the parent posteriorly in a close cluster, which is surrounded on all sides by a vacant space; they adhere to the adult by their posterior suckers, which are separated from the body by a very distinct constriction.

This singular species will subsequently be described at length under the name of Nephelis patelliformis, Nich.

Common in Toronto Bay, in from one to three fathoms.

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