and Systematic Position o/" Cheirolepis. 247 



palato-quadrate apparatus, and of the liyoid :uid branchiul 

 arches. 



licgarding the dentition of Cheirolepis tliere has also pre- 

 vailed some little obscurity. Agassiz describes tiie teeth as 

 being indeed of two sizes, but all arranged in one line, and 

 in that respect differing from the unequal dentition of his 

 " kSauroids ' and "Coelacanths," in which the smaller teeth 

 form a continuous external range. Pander and Huxley describe • 

 the jaws as being set with small conical teeth, but they were 

 unable to find any of tlie larger ones referred to by Agassiz ; 

 while Powrie, on the other hand, returns to the statement of 

 Agassiz regarding the larger and smaller teeth being in one 

 row. According to the specimens which have come under 

 my OAvn observation, tlie jaws of Cheirolepis were set along 

 the inner aspect of their dental margins with one row of 

 tolerably equal and rather closely set, sharp, and acutely 

 conical teetli, each having a marked inward curve, and, when 

 broken, displaying a large simple internal pulp-cavity. These 

 are undoubtedly the teeth referred to and figured by Pander, 

 who, however, seemed to expect that, according to Agassiz's 

 description, larger ones would be found among tliem. Now, 

 other teeth of a different size do exist — not larger, however, 

 but smaller ; and these form a row external to those first 

 described. The outer row of smaller teeth, the discovery of 

 which at once breaks down Agassiz's demarcation between the 

 dentition of Cheirolepis and that of his so-called " Sauroids " 

 and "Coelacanths," is not often seen, from the fact that the 

 edge of the jaw on which tliey are placed is almost invariably 

 found split off and adherent to the matrix of the " counter- 

 part," and thus the little teeth in question are hidden. But 

 by careful working out with the point of a needle, I have been 

 able to display some of them in two cases where a portion of 

 the edge of the jaw remained, as shown in Plate XVII. figs. 4 

 and 5. They are indeed veiy minute, being only about one 

 third or one fourth the length of the larger ones, which them- 

 selves only measure -pV inch in specimens of the ordinary size. 

 The dentition of Cheirolepis is thus reduced to a type very 

 frequent in Ganoid fishes, and which notably occurs in many, 

 if not in most, of the genera comprised in the family of 

 Palaioniscidse. 



The facts adduced in the preceding pages seem most satis- 

 factorily to prove not only that Cheirolepis^ as Prof. Huxley 

 lias already indicated, must take its place among those Ganoids 

 which he has brought together under his suborder of Lepi- 

 dosteidje, but also that among those Lepidosteids it must 



