376 Messrs. Hancock & Atthey on Reptile- and Fish-Remains 



structure ; but such specimens are mounted in balsam, which, 

 we have seen, is liable to render minute structure invisible. 

 It is therefore not improbable that the specimens of M. 

 Agassiz may have been mounted in this medium ; and it is 

 equally likely that the minute structure was not preserved in 

 the fossil examined by him. Such discrepancies must be ex- 

 pected in the examination oi fossils ; and accordingly we have 

 aheady seen that the minute structure in Ctenodus had escaped 

 the observation of that natm'alist. 



In Ageleodus we see another striking instance of the danger 

 of trusting entirely to the sections of objects not previously 

 miderstood. From this cause the denticles are described as if 

 their whole contour was seen, whereas there is nothing but 

 the mere stumps left in the section, the crowns all having been 

 cut away in making it. As the denticles are (as we have 

 already stated) recurved, they must necessarily, to a great ex- 

 tent, be removed in such a section as that figured. Had this 

 been previously known, the bases of the denticles could never 

 have been mistaken for their crowns, nor could the latter have 

 ever been described as " broader than they are high ;" nor 

 could it have been stated that they all " terminate obtusely ; 

 and this seems to be an original form, not due to wear or 

 abrasion." In fact, Prof. Owen describes merely a diagonal 

 section of the basal portion, and supposes that he describes the 

 whole denticle. This author has likewise been deceived into 

 the belief of the existence of a common pulp-cavity, by the 

 removal in the section of the osteo-dentine near the centre of 

 the specimen. Here all the substance has been ground away 

 in consequence of the lateral sigmoid bend before described. 

 A lateral section proves that no such cavity exists ; and, in- 

 deed, the large series of sections now before us, and which 

 were made many years ago, entirely disprove this assertion. 

 The inference drawn from the supposed presence of this cavity 

 is therefore of no avail. 



We have now examined the whole of the new genera and 

 species of Fishes and Batrachians proposed by Prof. Owen in 

 his paper published in the ' Transactions of the Odontological 

 Society," and find ourselves compelled to conclude that there 

 is positively not a single novelty in the whole series. Thirteen 

 genera were enumerated in the '' Absti-act" of the paper as 

 read; in the paper as published there are only twelve, one 

 (entitled " Oreodus ") having been withdrawn. It is unfor- 

 tunate that some circumspection had not been also observed 

 with regard to the remaining twelve, which, we fear, are fated 

 to fall into the like obscurity. We have found as we 

 approached the "New Coal Fishlets " that they gradually 



