REMAINS OF REPTILES AND FISHES. 103 



M. Agassiz's observations in Pygopterus, Lejndosteus, and Sau- 

 richthys, making in all eight in which a cap of enamel is found. 

 It is therefore highly probable that, when the subject is fully 

 investigated, enamel-tipped teeth may prove to be not at all 

 uncommon. But how has all this escaped the observation of 

 the learned author of the " Odontography ?" for escaped him it 

 assuredly has, or he never could have written as he has recently 

 done respecting Palceoniscus, AmhlyiAerm, Pygojjterus, Polypte- 

 rus, and Lepidosteus. 



AcANTHODOPSis Wardi, sp., Ef/ertoii. 



For some time past one of the authors of this paper has had 

 in his collection several jaws of a fish vidth large triangular teeth, 

 five or six in number, and appearing like processes of the bone ; 

 and of so peculiar a character are they that it was impossible to 

 say even to what family of fishes they belonged. It was not 

 until similar specimens were found associated with other remains 

 that any light could be obtained respecting them. At length a 

 crushed head or two were procured, exhibiting the same peculiar 

 jaws, with the like curious teeth attached, lying in juxtaposition 

 with the spines of one of the Acanthodei, partially buried in what 

 appeared to be the broken up skin of the fish, crowded with 

 minute rhomboidal scales. In one specimen the two pectoral 

 spines are placed in their proper position behind the head, and 

 united to it by the continuity of tissue, so as to leave no doubt 

 that they and the head belong to the same fish. The uniting 

 tissue, too, was mainly composed of granule-like scales of a loz- 

 enge form. A tail likewise of an Acanthodian has occurred in 

 the same locality, the scales on which agree both in size and 

 character with those found with the heads. It is therefore quite 

 certain that the jaws alluded to belong to the Acanthodei, not- 

 withstanding the abnormal character of the teeth, which in this 

 family are usually described as minute and conical. 



In the genus AcantJwdes, indeed, the teeth appear to have 

 been determined only in one species, though M. Agassiz states, 

 in his description of the genus, that fine teeth disposed in a 



