LEPIDOGANOIDEI. 167 



The type-genus of this family, Lepidotus, is remarkable 

 for the density and polish of its full-sized imbricated rhom- 

 boid scales ; it has a short dorsal fin opposite the anal, 

 and has two rows of fulcra to the anterior rays of all the 

 fins. The species range from the lias to the chalk ; one 

 species, indeed {Lepidotus Maximiliani), lingers, after the 

 commencement of the tertiary period, in the " calcaire grossier" 

 of Paris. 



In Notlwsomus and Opliiopsis the fin-fulcra are in a single 

 row, and the dorsal fin is very long. JSfotagogus and Propterus 

 have the dorsal fin almost cleft into two. 



Family XI. — Lbptolepid^;. 



The Ganoids of this family are homocercal, and have 

 small rounded scales. In the type-genus {Leptolepis, fig. 75), 



P 



Fig. 75. 

 Leptolepis sjprattiformis (Oolite, Solenhofen). 



the scales are extremely thin, yet a fine layer of ganoin 

 may be discovered in them, and has contributed to their 

 preservation. The teeth are minute and en hrosse, with 

 two of larger size in front of the mouth. The vertebrae 

 are ossified. Species of Leptolepis range from the lias 

 to the calcareous slates of Eichstadt. They are very com- 

 mon in the lithographic slates of Solenhofen and Pappen- 

 heim. 



A transitional step might be discerned on the derivative 



