of Connecticut and Massachusetts. 39 



entirely excluded by the posterior position of its dorsal. It may 

 therefore be ranked between the genera Scmionotus and Pholi- 

 dopliorus, being analogous to both in the structure of the tail, 

 and in its serrated fins, and to the latter in the articulation of the 

 rays. From the situation of the dorsal fin, I have thought the 

 name Catoptcrvs to be applicable to this new genus. This 

 name was originally applied by Agassiz to the genus Dipterus 

 of SedgewickandMurchison, but he was afterwards induced to 

 reject it, and restore the name given by the latter. I therefore 

 see no objection to naming the species Catojiterus gracilis. 



The specimen marked, No. 11, appears to be identical with 

 figs. 45 and 4S of Hitchcock, named by Agassiz, Eurynotus 

 tenuiceys. The genus Eurynotus is described by Agassiz as 

 having the anterior rays of the dorsal large and prolonged, and 

 the divisions of the tail unequal. In the figures of Professor 

 Hitchcock, it is the posterior rays of the dorsal which are 

 prolonged, and the tail represented as square and truncated. 

 To reconcile these figures with his generic description, Agassiz 

 has supposed the specimen of Hitchcock to have lost the long 

 anterior rays of the dorsal, and the tail to have been inadver- 

 tently drawn truncated, instead of forked. This latter suppo- 

 sition was not indeed improbable, as the same error is found 

 in the figure of the Palceoniscus fultus. The specimen of this 

 species, seen in England by Agassiz, and which he has figured, 

 is defective in a very important point, inasmuch as not only the 

 dorsal fin, but also nearly the whole of the back and part of 

 the tail are wanting. But the specimen before us, if it be the 

 same species figured by Hitchcock, shows that he was correct 

 in the representation of the dorsal,* but, unfortunately, it can 



* Since writing the above, I have been assured by Professor Hitchcock, that 

 his figure is correct in the representation of the dorsal, and that its peculiar form 

 could not have been accidental, as he had in his possession numerous individuals 

 of this species, all of which coincide in this particular. 



