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Show 96 PROE. HOWES ON SYNOSTOSIS AND [Feb. 6, take for example the haemal ones, the 13th measures in total length 1 inch, the 18th f of an inch, and the 23rd 1-^ inch. In the normal iudividual possessed of a straight backbone, the corresponding elements exhibit a progressive increase in length-here they have undergone an adaptive variation, whereby au approximately normal and regular contour of the creature's body was unquestionably maintained; and the extent to which, as the result of pure adaptation, this had been carried is most significant in the flexion to the utmost of certain of the posterior haemals and neurals depicted in the sketch (a.h. 41-46, a.n. 35-39). O n comparison of as much of this skeleton as is preserved with the corresponding parts of a normal individual, an increase in vertical diameter proportionate to diminution in length becomes at once apparent. The total length of the vertebral column as it lies flexed is 6 inches, its actual length measured along the curves 7f inches, and its longest outstanding process, haemal or neural, does not exceed 1J inch. I a m in possession of one normal skeleton of identical proportions in which arches 25 to 28 are longer; and it would appear therefore more than likely that skeletal growth in the vertical plane was under rather than over the average in this remarkable individual. Beyond this, the specimen bears no marked peculiarities not apparent in the accompanying figure. There was no co-ossification of parts, but the neural spines of vertebrae 7, 8, and 10 bear syn-ostotic enlargements (sy.) indicative of preceding fracture. There was no lateral displacement of either the vertebral bodies or their associated arches, beyond a feeble irregularity of certain of the haemal arches, not improbably due to shrinkage in drying. The nearest approach to a similar condition to this which I have been able to find is that of a Perch in the Hunterian Series of the Royal College of Surgeons (figs. 3 a and 3 6). That, however, shows but three marked sinuosities, and the third of these, in contradistinction to that of the Sole, is accompanied by a displacement of the tail to the animal's left side1. Salient points of agreement with the Sole are, however, forthcoming in the otherwise non-sinuous contour of the animal's body, and in the fact that the shallowest spinal sinuosity is most nearly median and the deepest one posterior in position. The full number of vertebrae (viz. 42) 2 are present, and the detailed differences between the curvature of this animal's backbone and that of the Sole are sufficiently expressed in the accompanying illustrations (cf. figs. 16 and 3 6). As with the Sole, the approximation of the ends of the spinal column consequent on the curvature was accompanied by an increase in vertical diameter of the body, though to a greater extent than in that animal-for, while the greatest vertical diameter of a normal Perch (excluding its dorsal fin) is rather more than ^th its 1 There is in the College of Surgeons' collection an undissected Perch having a precisely similar curvature (No. 361 of the Catalogue cited). Cf. Postscript, p. 100. 2 Cf. Giinther, Introd. to the Study of Fishes, p. 53. |