262 Mr. J. Alder on Euplocamus, Triopa and Idalia. Mr. Thompson's drawings and these specimens is certainly very-great, though the anterior end in mine is rather more closed than in his, by the bending over of the edges through which the ten-di-ils of the two sides have become entangled together. None of the markings are so strong as in the figures, the transverse mark-ings on the broad flat sides being scarcely perceptible in any of the specimens, and the striae on the flattened edges not extending in general very far from the posterior end, where they are in some specimens tolerably strong and extend over the inner edge of the rim as shown in the figure. The dimensions in length, at least of my specimens, were all less than those of Mr. Thompson, viz. Extreme length 4 inches. Width H „ Thickness rather more than \ „ The colour when fresh was a pale horn as usual, but becomes brown by keeping. As regards the period of protrusion, from May when I procured my first specimens until the end of November and beginning of December the fish became scarce, when they again appeared in the market, and on the 27th of December I procured some fresh eggs, one pair of which was said to have been taken from a large female then lying opened before me. Others I saw subsequently, and in one I observed the ovaries to contain eggs still in a soft state and without their covering ; this was a large specimen, mea-suring 28 inches. There can therefore be no doubt that the eggs of these fishes are protruded at least at two periods of the year. XXXVII. — Note on Euplocamus, Triopa and Idalia. By Joshua Alder, Esq. ' ' I In the second volume of the ' Enumeratio MoUuscorum Sicilise,' Dr. Philippi under the head of Idalia (to which he now refers his genus Euplocamus) makes some strictures upon a notice that ap-peared in this Journal (vol. vi. p. 217) from Professor E. Forbes, stating that the lateral appendages of Euplocamus of Philippi {Triopa of Johnston) had no vibratile cilia, and consequently were not branchial. The same notice also stated that the lateral ap-pendages of Tritonia and Eolis were ciliated, but the branchial appendages of Polycera were not so. To these observations Dr. Philippi makes several objections. In the first place, after asking on what species of Euplocamus the observations were made, he says that a mere inspection of the figure of his E. croceus, without any microscopic disquisition, will show that the lateral appendages serve the office of respira-tion, and from this species, he adds, the transition is evident to
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