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Show 100 PROE. HOWES ON SYNOSTOSIS IN FISHES. [Feb. 6, faces of those which bound these. That the muscular rather than the skeletal system has been, as it were, at fault, is largely proved by the fact that there is no marked falling off in either the bulk or density of the latter where disturbance occurs ; and the most logical conception of the determining cause seems to m e that of an inequality of development, either in bulk or elasticity (and probably the latter), of certain muscles-those affected having either, as it were, lagged behind the skeleton or become fixed in a state of tonic contraction. If this be so, while approximation of the parts of the vertebral column stands out as the ultimate result of the disturbance, w e m a y conveniently at least distinguish between the sinuous condition or approximation by plecospondyly l (figs. 1 and 3), and the compressed one or approximation by sympieso-spondyly2 (figs. 5 and 6). The specimen last described is of interest in another connexion. Cunningham, in his monograph on the Sole (loc. cit. p. 39), gives 50 as the total number of vertebrae present, and points out that the first one " is rudimentary" and possessed of " two small dorsal processes which lie along the front edge of the base of the dorsal processes of the second vertebra, but do not unite to form a spine." There can be little doubt that these " dorsal processes" of the first vertebra are but a partially developed pair of neural arches- in the specimen under consideration they are reduced to absolute insignificance (fig. 4 6). This greater simplification of the first vertebra is the more interesting, as but 48 instead of 50 vertebrae are present, and as the well-defined characters which diagnose the 5th and 11th vertebrae of the normal spine are here realized by the 4th 3 and 10th. P.S., March 1, 1894.-During the passage of these notes through the press, the College of Surgeons' Perch, No. 361 (cf. footnote, p. 96) has been dissected, thanks to the kindness of Prof. Stewart. The curvature of its backbone is, most interestingly, identical with that of figs. 2 a and 3 6, but of greater amplitude, as is expressed externally by a marked elevation of the trunk cephalad of the first dorsal fin. The vertebrae which mark its vertices number 7-8, 18, and 30. But 39 free vertebrae are present, and the displacement to the left side involves those numbering 20 to 35. Except for a feeble depression of the mid-dorsal region, the contour of the body is regular, and the arches, intermuscular bones, and associated parts are correspondingly modified. 1 irXeiceiv, to twist; (Tiroi'SvXos, a vertebra. 2 (rvfnrieZeiv, to squeeze together. 8 In this case on the left side only. |
