PEOFESSOE HYETL's ANATOMICAL KOTES. 103 



11. On intervertebral Synostoses and Suturce in JFish. 



I have collected together from almost every quarter of the world, 

 a large series of fish skeletons, numbering several hundi^eds. When 

 siu-veyiug from time to time my treasures, I have been struck by the 

 many examples occurring among them, of what, if it occurred in the 

 human subject, would be considered a disease : I I'efer to the osseous 

 union of a greater or lesser number of vertebra? into a solid mass, 

 with the total disappearance of all intervertebral articulations, and of 

 every vestige of cartilage or articular cavity, so that every ti'ace of 

 mobility has gone. rfteiitzs TOiTOt^oq birB 'f 



The number of coalesced vertebrae is from two to six, and this 

 synostosis takes place more frequently in the tail than in the trunk 

 of the fish. When one remembers that the locomotive powers of a 

 fish chiefly depend on the extreme flexibility of its vertebral colimm, 

 one would think that the diminution of this flexibility by the 

 abolition of the intervertebral articulations, would not only cause 

 some inconveniences to the creatm-e, but even endanger its existencei^ 

 This is, however, obviated by the fact that the confluent vertebrae are 

 not larger than the non-confluent ones, their length being so much 

 reduced, that the five coalesced vertebrae are not longer than one ; 

 and a slight fraction of a non-coalesced one. It is a very remark- 

 able sight to see such a synostotic series of vertebrae in the tail of 

 some powerful fish; and this too, not by any means the result of 

 pathological deformity, there being no callosity present to suggest' g,, 

 mechanical injury, and no deposits of calcareous matter to induce us 

 to regard the synostoses as a senile metamorphosis; for it occurs iu 

 both old and yoiuig individuals, and in those of both sexes. The 

 union is oftentimes so perfect that it is only by the presence of the 

 two superior or inferior spinous processes, that we perceive that 

 it has taken place; the intervertebral foramena appear never to 

 be perfectly obliterated, though they are exceedingly diminished iu 

 size. 



The synostosis is, without doubt, of a physiological character, and 

 it must take place very early in life, when the length of the bodies 

 of the vertebrae is so short, that two, three, four, or five such lengths 

 is equal to the length of a single vertebra of a fully grown-up 

 individual. When the increase in length is stopped, the increase in 

 circumference continues, as in the non-synostosied vertebral bodies. 

 This synostosis does not appear to occur in any of the short-bodied 

 fishes. It does not occur in the short-bodied Sparoid, Moenoid, nor 

 Squamipennate fish, nor in any Labyrinthoid, but in most of the other 

 families it occurs the oftener, the longer the fish. In the Eel tribe 

 (especially Gymnoius), iu the Mormi/rus {kut £^oxr]y Gymnarchus'), 

 two, three, and even four portions of the vertebral column are 

 affected with this vertebral synostosis. 



Another instance of solid and immovable vertebral imion is to be 

 found iu the genus Ostracion, the body of these curious fish being 



