118 MESSRS. HANCOCK AND ATTHEY ON 



Prof. Owen describes merely a diagonal section of the basal por- 

 tion, and supposes that be 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, indeed, the large series of sections now 

 before us, and which were made many years ago, entirely dis- 

 prove 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. Thu'teen 

 genera were enumerated in the "Abstract" of the paper as read, 

 in the paper as published there are only twelve, one (entitled 

 " Oi'eodiis'') having been withdrawn. It is unfortunate 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 dwindled away, and at length en- 

 tirely disappeared ; or rather we perceived that they never had 

 had any real existence, and that the " Minnows and Sticklebacks" 

 of the Northumberland coal-shales have yet to be discovered. 



EXPLANATION OF THE PLATES. 

 PLATE I. 



Fig. 1. Sternal plates of Pteroplax cornuta, about half the natural size: 

 a a, lateral plates ; b, posterior portion of central plate appear- 

 ing from beneath the former ; c, posterior process. 



Fig. 2. View of underside of central sternal plate, two-thirds natural size : 

 a, perfect lateral wing or lobe ; b, posterior process. 



