244 IOWA GEOLOGICAL SURVEY 



is the origin of the name ' ' Coelacanth" which has been conferred 

 on the family. This character is especially striking in the typical 

 genus Coelacanthus. To this singular structure of the bones is 

 added another more apparent and more external character, viz., 

 the form and disposition of the fins, and the mode of articula- 

 tion of the rays ; and in the first place, most of the rays are stiff, 

 or only articulated at their ends. Their combination with the 

 apophyses [neural arches and spines] and inter-apophysial 

 [interspinous] bones is very singular, especially in the caudal 

 fin, the rays of which are supported by interspinous bones; an 

 arrangement which in other fishes is found ordinarily only in 

 the anal and the dorsal [caudale in the text]. Lastly, the verte- 

 bral column is prolonged more or less distinctly between the 

 principal lobes of the caudal fin, so as to form a median taper- 

 ing process. . . ." 



Of the genus Coelacanthus proper, Professor Agassiz re- 

 marks (p. 170) : 



"This genus, which I regard as the type of the family, was 

 long known to me only by fragments ; but these were so different 

 from most other ichthyolites that I did not hesitate to incorpo- 

 rate them into a distinct genus. What especially struck me was 

 the form and the structure of the fins, their relation with the 

 interspinous bones, and the manner in which the apophyses 

 [vertebral arches and spines] are united on the one hand with 

 the bodies of the vertebrae, and on the other with the inter- 

 apophysial [interspinous] bones. The apophyses divide at 

 their bases into two branches, forming a fork, which embraces 

 the body of the vertebra; to this apophysis succeeds an ossicle 

 which, instead of being interposed between two apophyses, is 

 fitted on to the end of one, so as to form its direct prolongation. 

 The ray properly so called, the longest of the three pieces, is also 

 forked at its base; its extremity alone is jointed, but never bi- 

 furcated. These three pieces, the apophysis, the inter-apophysial 

 bone and the ray, are of subequal length and all three are 

 hollow. . . . 



"This singular structure characterizes most of the rays which 

 lie at the posterior part of the trunk; now, as usually only the 

 anal and the dorsal have inter-apophysial bones, T at first con- 

 cluded that these two fins must be excessively developed ; and 

 what helped to strengthen this idea was the fact that the verte- 

 bral column appeared to be continued beyond the two azygous 

 fins, to form further on a bundle of very small articulated 

 rays, attached directly to the vertebrae. But Lord Enniskillen 's 



