1894.] PROF. HOWES ON SYNOSTOSIS IN FISHES. 95 



1. On Synostosis and Curvature of the Spine in Fishes, 

 with especial reference to the Sole. By G. B. Howes, 

 F.L.S., F.Z.S., Assistant Professor of Zoology, R. Coll. 

 Sci. Lond. 



[Keceived January 16, 1894.] 



(Plate XII.) 



A short time ago my pupil Mr. W. L. S. Loat placed in my 

 hands for examination a backbone of the Sole (Plate XII. figs, la 

 and 1 b) which presents the unique abnormality of a quinque- 

 recurrent curvature, such as I believe has never before been recorded. 

 On turning to that rich storehouse of teratological material, theEoyal 

 College of Surgeons' Museum, for specimens which might throw 

 light upon this extraordinary backbone, I have been so fortunate 

 as to meet with facts which, while they show the Sole's vertebral 

 column to be liable to a wide range of structural aberration, give us a 

 clue to at any rate the determining cause of that form of curvature 

 herein dealt with (cf. infra, p. 100) V By a fortunate coincidence, 

 two malformed backbones of this fish (figs. 4 a and 5) had been 

 quite recently presented to that Institution by Prof. Bland Sutton; 

 and to that gentleman, together with the Council of the CoUege 

 and ray ever willing friend Prof. Chas. Stewart, I tender my 

 thanks for permission to examine and report upon their 

 specimens. 



Mr. Loafs specimen was that of an old fish having an estimated 

 length of from 9 to 10 inches, and 47 of its vertebrae were preserved, 

 the terminal ones ("? 3 in number) having been lost. The backbone 

 of the normal Sole is straight, except for a feeble arching of its 

 anterior 14-16 vertebrae ~. In this example (fig. 1 a) it was, as 

 already stated, thrown into a series of fixed sinuosities, five in 

 number as reckoned by their vertices, a marked depression 

 preceding the terminal one. All the vertebrae but the anterior 

 3 or 4 and that lying at the base of the second dip were more or 

 less displaced in the vertical plane, and the minor details of the 

 disturbance may be more readily gleaned from the accompaning 

 figure (which is an accurate copy of a photograph) than expressed 

 in words. There can be no doubt that the aberration was con- 

 genital, for the vertebral bodies (which were fully formed and 

 independent throughout) conform in many cases to sections of a 

 circle, owing to the adaptive modification of their articular faces. 



More interesting, perhaps, than this is the condition of the aixmes, 

 as is at once evident from the fact of the practical absence of any 

 marked sinuosity of the contour described by then free ends. To 



1 ''The causes producing congenital curvature of the spine are unknown,'' 

 K. Coll. Surgeons' Descr. Cat. of the Teratological Series, 1893, p. 94. 



- Cf. Cunningham, ' A Treatise an the Common Sole.' Plymouth : Marine 

 Biol. Assoc, 1890. 



