FISHES OF CEARA, BRAZIL — JORDAN AND BRANNER 29 



The species cannot be fully described without better material, but 

 in any event it may be known at once among Brazilian Cretaceous 

 fishes by the character of the large convex undivided opercle, very 

 conspicuous in all these specimens. It is also distinguishable at once 

 from Calamopleiinis, Notelops, and Tharrhias by the much greater 

 distance from the gill opening to the dorsal fin. This is greater than 

 length of head or than depth of body. At the request of Senhor Dias 

 da Rocha, its discoverer, this genus is named for his native province 

 of Ceara, where the type was obtained ; the species is named for 

 Senhor Rocha himself, who brought together this remarkable col- 

 lection. 



The counterpart of No. 5 is in the department of geology at Stan- 

 ford University ; the type is with Senhor Francisco Dias da Rocha at 

 Ceara. 



It may be noted that a peculiar interest attaches to this, as to any 

 other accessible portion of the Cretaceous fish fauna. This period 

 represents the decline and partial disappearance of the ganoid types, 

 with rhombic enameled scales, represented by Belonostomus and Lep- 

 idotes. This is contemporaneous with the first appearance of the 

 lowest of the bony fishes, of which the Leptolepidae and the Elopidse 

 are both among the most primitive, followed later by Chirocentridae, 

 Osteoglossidse, and other forms allied to the herring. 



