VERTEBRATA 97 



having any probable claims to vertebrate rank ; and to this 

 admission must be appended the remark, that the parts referred 

 to jaws and teeth may be but remains of the dentated claws 

 of Crustacea. With regard to the fossils called " Conodonts," 

 on which the main part of M. Pander's evidence of lower 

 Silurian fishes rests, the following remarks, penned after 

 microscopic examination of original specimens, are applicable 

 to them. 



Minute, glistening, slender, conical bodies, hollow at the 

 base, pointed at the end, more or less bent, with sharp opposite 

 margins, might well be lingual teeth of Gastropods, acetabular 

 hooklets of Cephalopods, or teeth of cartilaginous fishes. 

 Against the latter determination is the minute size of the 

 " Conodont " bodies. Their basal cavity doubtless contained 

 a formative pulp, but the proof that the product of such pulp 

 was " dentine " is wanting : the observed structure of the 

 hooklet presents concentric conical lamella? of a dense 

 structureless substance, containing minute nuclei or cells. 



In some specimens the base is abruptly produced and 

 divided from the body of the hooklet by a constriction — a 

 form unknown in the teeth of any fishes, but presented by 

 certain lingual teeth of Gastropods — e.g., the lateral teeth of 

 Sparella. In other Conodonts the elongated base is denticulate 

 or serrate, as in the lateral teeth of Buccinum and Chrysodomus. 

 It is improbable, however, that they belong to any conchiferous 

 toothed Mollusk, the shells of such being wanting in the 

 deposit where the Conodonts are most abundant. 



The more minute hooklets have a yellowish, transparent, 

 horny appearance ; the larger, perhaps older ones, present a 

 harder whitish appearance. Their analysis by Pander yielded 

 " carbonate of lime," carbonic acid being evolved by application 

 of dilute nitric acid, and oxalic acid producing an obvious pre- 

 cipitate. Some English analysts have believed that the Cono- 

 donts yielded a trace of phosphate of lime. 



H 



