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Show 586 MR. W. BATESON ON ABNORMAL [Julie 17, right or adradial facet of the axillary 32nd brachial has no pinnule till its third joint, which is not a syzygy, though the fourth is; but in other respects the arm is normal. The second facet of the axillary 30th brachial bears a normal arm of about 60 joints, with a pinnule on the second and a syzygy on the third. Thus, then, the axillary 29th brachial of the primary arm b2 gives rise to four well-developed arms, two of which bear bifid or trifid armlets, in addition to the larger bifid armlet on the 28th brachial. " The primary arm e, does not seem to have undergone any regeneration and is normal to the 40th brachial. The 41st is a syzygy and the appendage of its epizygal is a short armlet of three joints, the second and third of which bear pinnules laterally, while its main axis is also continued on in the form of a pinnule. The 42nd brachial has a similar armlet, with but one lateral pinnule. The 43rd is axillary without a syzygy, its adradial branch being a normal arm with some 40 joints remaining, the second and fourth of which have pinnules, though the third has not. The 44th joint of the primary arm seems to be a syzygy; and its epizygal, though not regularly axillary, supports an arm which has the first pinnule, as usual, on the second joint, but on the inner instead of on the outer side. The next five joints are all enlarged and bear bifid or trifid armlets, while the remainder of the arm is normal, with regularly alternating pinnules." Variations in the number of parts and even in the primary symmetries are well known among Echinoderms, but Dr. Carpenter informs me that this specimen is quite unlike anything of the kind which he has previously met with. V.-Pilchards (Clupea pilchardus) with the Number of Scales abnormally increased. In the ' Proceedings' of this Society for 1887 (p. 129) the late Mr. F. Day described a specimen which he believed to be a hybrid between the Herring (C. harengus) and the Pilchard. The specimen was sent by Mr. Dunn, of Mevagissey. Its peculiarity lay in the fact that the scales on the left side were very many more in number than those on the right side. The number of scales along the lateral line is given as 32 on the right side and 51 on the left. Mr. Day adds that the ridges on the operculum, which are characteristic of the Pilchard as compared with the Herring, were better marked on the right side than they were on the left, though they are stated to have been very distinct on the left side also. In the specimen described the gill-rakers were 61 in the " lower branch of the outer branchial arch " (viz. the bar consisting of the first hypobranchial and ceratobranchial), and it is mentioned that this number is intermediate between that found in a Pilchard (71) and in a Herring (48); but whether this intermediate number was found on the side showing the " hybrid " characters, or on the other, or on both, is not stated. These gill-rakers are also said to have been intermediate in length between those of a Pilchard and those |
