v 



96 PROF. HOWES OK 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 ly 1 ^ inch. In 

 the normal individual possessed of a straight backbone, the corre- 

 sponding elements exhibit a progressive increase in length — here 

 they have undergone an adaptive variation, whereby an approxi- 

 mately 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). 



On 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 lg inch. 1 am 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 vertebra? 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?)). That, however, 

 shows but three marked sinuosities, and the third of these, in con- 

 tradistinction to that of the Sole, is accompanied by a displacement 

 of the tail to the animal's left side 1 . Salient points of agree- 

 ment 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) a 

 are present, and the detailed differences between the curvature of 

 this animal's backbone and that of the Sole are sufficiently ex- 

 pressed in the accompanying illustrations (cf. figs. 1 b and 3 b). 



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 haviug 

 a precisely similar curvature (No. 361 of tbe Catalogue cited). Cf. Postscript, 

 p. 100. 



2 Cf. Giinther, Introd. to the Study of Fishes, p. do. 



