THE FAMILY CCELACANTHINI. 



41 



The common characters^ classification^ and distribution of the 



CCELACANTHINI. 



The fossil fishes which have been described above under the 

 names of Coelacanthus, Undina, Holophagus, and Macropomay 

 have the following characters in common : — 



1. The body is covered with thin cycloidal scales, the exposed 

 portion of which is ornamented with tubercles or ridges of 

 enamel. 



2. There are two dorsal fins, the anterior supported by a 

 single broad and plate-like interspinous bone ; while the posterior 

 has a forked intersj)inous bone. There is a single anal fin, and a 

 very large caudal, the upper and lower lobes of which are equal ; 

 the spinal column, which traverses it without being at all bent up, 

 ending in a filament with small supplementary fin rays.* 



In the caudal fin, interspinous bones are interposed between 

 the fin-rays and the neural and subvertebral spines. 



3. The paired fins are obtusely lobate. The pectoral arch is 

 strong and well ossified, and there are two large pelvic bones. 

 The fin-rays of all the fins are not articulated at their proximal 

 ends, and are longitudinally undivided. The ventral fins are placed 

 but very little behind the anterior dorsal, and the anal lies below 

 the posterior dorsal. 



4. The spinal column is unossified, the notochord being persis- 

 tent, and only the neural and subvertebral arches ossified. If ribs 

 existed at all, they were remarkably small. 



5. The roof of the skull is formed by a parieto-occipital and a 

 frontal shield, which meet at an obtuse angle. The surface of 

 each of these is ornamented with tubercles of enamel. 



6. There is a large pterygo-suspensorial " bone representing 

 the hyomandibular, quadrate, and pterygoid bones of ordinary fishes. 



7. There are two jugular bones and no proper branchiostegal 

 rays, 



8. The branchial and hyoidean arches are well ossified, and 

 there is a median bone in. the branchial series which has a spa- 

 tulate posterior termination (not observed in Holophagus and 

 Undina), 



9. The air bladder has ossified walls. 



10. The teeth are for the most part " en brosse " or tubercle- 

 like and minute ; but a few are larger, acutely pointed ( Undina ? 

 Holophagus?). These larger teeth exhibit no plications at their 

 bases. 



These being the common characters of the Coelacanthini, the 

 next point is to obtain clear definitions of the several genera which 

 compose the group. 



Codacanthus is readily enough distinguished from the rest by 



* This peculiarity of the caudal fin has not not been actually observed in Macro- 

 poma ; but it is hardly doubtful that the cretaceous genus resembled the others in this 

 particular. 



