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Show 164 MR. W. BATESON ON THE COMMON PILCHARD. [Mar. 6, illustration has been lent to us. This bird has now moulted its nestling-plumage altogether, and has assumed the first feather-plumage, in which it is nearly of a uniform black. The young bird was probably not more than 2 or 3 months old when received, and therefore would appear to remain about 7 or 8 months in its nestling-plumage. Mr. W . Bateson exhibited six specimens of the C o m m o n Pilchard (Clupea pilchardus) showing variation in the number and size of the scales. The specimens had been received from Mr. Matthias Dunn, of Mevagissey, Cornwall. In each of them the scales over a greater or less area of the body were smaller and more numerous than in the normal fish. Similar specimens were exhibited to the Society by Mr. Bateson in 1890 and had been described in the Proceedings * as examples of abnormal repetition of parts. In that paper reference was made to an account of a similar specimen that had been given by the late Mr. F. Day2, who took a different view, being of opinion that the fish was a hybrid between the Pilchard and the Herring. For reasons then given it was urged that the evidence of hybridity was unsound, and it wras represented that the abnormality was more probably due to variation. The new cases fully bore out the view then taken. Except in the matter of the scales, each of the six examples was in all respects a true Pilchard, having the normal sculpture on the opercula, the high number of gill-rakers characteristic of the Pilchard, and the histological features normally found in the scales of the Pilchard. In the matter of the gill-rakers the lowest number seen in the abnormal fishes was 70 and the highest 89, most of them having about 78. The numbers seen in normal Herrings are considerably lower than these. In four of the new specimens the small abnormal scales extended over the posterior half of one side only. In one specimen both sides were almost uniformly covered with the small scales. In the sixth specimen the posterior half of one side showed the small scales, and on tbe other side there was in about the middle of its length a circular patch of very small scales, the remainder of the scaling being normal or nearly so. Unfortunately the specimens had been somewhat rubbed and the precise numbers of tbe scales cannot confidently be given. Speaking in general terms, it may be said that in the areas of abnormal scaling the size of the scales was about half that of the normal scales. All the specimens were well grown and in good condition, ranging from 7 to 8i inches in length. 1 Proc. Zool. Soc. 1890, p. 586. 2 Op. cit. 1887, p. 129, pi. xv. |
