Structure and Classification of the Asterolepidaj. 495 



the name of A. maximus, Xg., sp., the name being fortanately 

 suited to its large size, as median dorsal plates sometimes at- 

 tain a length of 6 inches. 



BoTHRiOLEPis, Eichwald, 1840. 



(Painjihracttis, A^assiz ; Homotlwrax, Ag. ; Asterolepis, Pander, pars ; 

 Pterichthys, Ag. et cet. aiict. pars ; Bothriolepis, Ag., pars.) 



BothrioJepis was founded hy Eichwald upon certain plates 

 or fragments of plates occurring in the Old Red Sandstone of 

 Russia 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 hira 

 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 sturgeon^, 

 with a rough shagreened skin or smooth enamelled scales 

 between them. By Agassiz Bothriolepis was placed among 

 the " Coelacanthi," and though the plates figured by him as 

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

 racter, he gave the name of Bothriolepis favosus to an un- 

 doubted Rliizodont. In establishing the family of Placo- 

 dermata to include the Cephalaspidge of Agassiz except Gepha- 

 lasjjis, M'Coy (5) rightly included Bothriolepis, and Pander 

 went so far as to assign to it a place among the synonyms of 

 Asterolepis, Eichw., along with Pterichthys, Ag., and many 

 other names. 



However, the dorsal plate figured later on by Eichwald (2, 

 pi. Ivi. fig. '6) as belonging to his B. ornatus not only stamps 

 it as Asterolepid, but leads us also to suspect that it is generically 

 different both from Asterolepis and Pterichthys, and that this 

 is the case was clearly shown by Lahusen (11). Describing 

 a head with a portion of tlie body attached, as well as the two 

 median dorsal plates and some other fragments of the body 

 and arms of a species to which he gave the name of B. Pan- 

 deri, Lahusen j.ointed out, first that the course of the cephalic 

 furrows (lateral line system) was not the same as in Astero- 

 lepis ; second, that the postmedian plate was different in 

 shape'; third, that there was no os ternnnale', fourth, that 

 the articular plates of the arms were longer. But when he 

 speaks of the arms being more simple in structure than those 

 of Asterolepis and we compare his figures, it is quite clear that 

 he had before him only the proximal segment of the limb ; 

 and it must also be noted that in some cases he regards the 

 giooves of the cephalic lateral line system as sutures, or at 

 least as former sutures, and so very considerably increases 

 the number of bones which he allots to the cranial shield. 



