648 FOURTH UEPORT 1834. 



belong to two species only. Amongst the Orkney fishes there 

 are two very remai'kable genera, resembling the Acanthodes of 

 the coal formation, also having very small scales ; but the new 

 Cheiracanthus is fm-nished with a spine in the pectoral fin only, 

 and the other, the Cheirolepis, instead of having the spine, is 

 provided Avith a row of small scales. M. Agassiz has been con- 

 vinced by the examination of many specimens that the genus 

 DijJterus has two dorsal fins and two anal fins, which sometimes 

 are opposite one another and sometimes alternate ; and these 

 are types of two genera, the Diplojiterus and the Plei(ypterus. 



The fishes from Burdiehouse are also very numerous ; in their 

 characters they agree with those of the coal formation, but are 

 more removed from those of Saarbriick than are the remains 

 found at Newhaven. 



The most remarkable amongst them is an animal which, from 

 the structure of its teeth, might be considered as a reptile, and 

 which must have been of very considerable dimensions ; but 

 which, from its skeleton and its scales, is decidedly a fish. This 

 animal forms a new genus under the name Megalichthys, and 

 confirms the opinion formerly expressed, that we observe in 

 older deposits organic remains which, with the usual characters 

 of their family, unite the characters of the types which have 

 made their appearance at a more recent period. Unfortunately, 

 no perfect specimen of the Megalichthys has been found, and 

 it has not been possible to bring together all the different parts 

 of the skeleton. Another new genus, related to the Amhlypte- 

 rus, has a long dorsal fin extending beyond the ventral fin and 

 the anal fin, and may be named the Em'onotus. The other 

 species belong to the genera Pygopteriis and Amhlypterus. 

 Very large ichthyodorulites occur not unfrequently, and seem to 

 belong to the genus Hyhodus.* 



At Newhaven eight species occur, of which some bear a con- 

 siderable resemblance to the fossil fishes of Saarbriick, though 

 still distinguished from them by some characters. They belong 

 to the genera Pygojjterus, Amhlypterus, and Palceoniscus ; and 

 there is one species which will in all probability form a new 

 genus, as it differs considerably from the genus Acrolepis. 

 Placoidian fishes are also found, but only in fragments, so that 

 their specific characters have not been determined j and there 



* M. Agassiz was led by the specimens which he subsequently examined at 

 Leeds, to consider the larger relics of Burdiehouse as belonging to two large 

 animals instead of one. The large scales and the long bones are referred by 

 him to Plammolipis, while the large teeth and round scales are supposed to be- 

 long to the animal he has named Megalichthys Hibberli. 



