Structure and Classification of the Asterolepidse. 35 



surface (Fig. 2) the antero- and postero-lateral margins show 

 each a narrow surface, x and y, which overlap the anterior 

 and posterior dorso-laterals respectively. Isolated speci- 

 mens of the dorso-lateral plates show corresponding surfaces 

 on their outer aspects. The rest of the creature, as I have 

 said, resembles PtcrichthySy but the carapace is more de- 

 pressed, the anterior and posterior dorso-lateral plates being 

 narrower. The limbs are short and are similar in construc- 

 tion to those of the last-named genus ; and thougli I have 

 seen little of the head, what I have seen appears to corre- 

 spond. As regards the tail, as no really entire specimen of 

 the creature has occurred, it is difficult to speculate ; but 

 numerous rounded scale-like bodies occurring in the same 

 beds may possibly be referable to this part. 



I therefore propose to refer this species to Asterolepis under 

 the name of A.'maximus, Ag., sp., the name being fortunately 

 suited to its large size, as median dorsal plates sometimes 

 attain a length of 6 inches. 



BoTHRiOLEPis, Eichwald, 1840. 



{Pamphractus, Agassiz ; Homothorax, Ag. ; Asterolepis, Pander, pars ; 

 Pterichthys, Ag, et cet. auct. pars; Bothi'iolepis, Ag., pars.) 



Botliriolepis was founded by Eichwald upon certain plates 

 or fragments of plates occurring in the Old Ked Sandstone of 

 Eussia which differed from those of Asterolepis in having the 

 surface pitted instead of tuberculated. From his very brief 

 original description (1) it is evident that he had before him 

 fragments of a creature allied to Pterichthys; but unfortu- 

 nately he ascribed teeth to it, and imagined its scutes to be 

 arranged in longitudinal rows, like those of the sturgeons, 

 with a rouo'h shao-reened skin or smooth enamelled scales 

 between them. By Agassiz Bothriolepis was placed among 

 the " Ccelacanthi," and though the plates figured by him 

 as B. ornatus, Eichw., are Asterolepid (or Pterichthyid) in 

 character, he gave the name of Bothriolepis favosus to an 

 undoubted Ehizodont. In establishing the family of Placo- 

 dermata to include the Cephalaspidae. of Agassiz except 

 Cephalaspis, M'Coy (5) rightly included Bothriolepis, and 

 Pander went so far as to assign to it a place among the 



