72 BULLETIN UNITED STATES GEOLOGICAL SUEVEY. 



tebr}© are short, and the neural and hsemal spines are well developed, 

 while the ribs are weak. Vertebrae : Dorsals to first descending inter- 

 neural spine, 19; of the caudal series, 12. 



There is no indication of an adipose fin. The posterior portion of the 

 dorsal fin is lost, so that the number of rays cannot be ascertained ; nine 

 interneurals remain. The pectoral fin is long and slender, but does not 

 reach to the ventral. Anal rays not elongate, nine in number. The 

 bones of the head are so thin that their boundaries are not easily deter- 

 mined. The opercular apparatus is well developed, and there are two 

 approximated parallel ridges on what appears to be the top of the head. 

 The scales are so thin that their number is not ascertainable. A 

 peculiarity of the species, from which it derives its name, is that its 

 sides are marked by longitudinal bands of a darker color than the inter- 

 vening spaces. There are six above the vertebral column and six below 

 it. I cannot determine that this appearance is due to rows of scales j 

 but they rather seem to be true color-stripes. 



Measurements. 



M. 



Length of head of No. 1 0.012 



Length to base of dorsal fin 0.032 



Depth half-way between head and dorsal fin 0.006 



Length of caudal region of No. 2 - 0.019 



Length of caudal fin - 0. 009 



Depth at first anal ray i 0. 005 



Depth at base of caudal fin 0. 0045 



Niobrara Cretaceous of Dakota ; found by Dr. Sayden. 

 Sardinius percrassus, sp. nov. ^ 



The block which contains specimens of Tricenaspis virgulatus, Lepto- 

 tracJielus longipinnis, Sardinius lineatus, and another species undeter- 

 mined, contains also the very distinct fish now described under the name 

 at the head of this paragraph. It is distinguished from the other Sar- 

 dinii by its very robust form, and from the 8. nasutulus by the origin of 

 the ventral fin being behind the perpendicular of the first dorsal ray. 



The anterior part of the head is damaged ; the operculum is distinct. 

 There is an elongate postclavicle, and the position of the small pectoral 

 fin is normal. The origin of the dorsal fin is much nearer the head than 

 to the caudal fin ; its raj's, like those of all the other fins, are slender. 

 The ventrals originate under the fifth dorsal ray, and are supported by 

 slender femora, which appear to be undivided, and converge to an acute 

 junction anteriorly. The anal fin is short and entirely behind the dorsal. 

 The neural spines and interneurals and iuterhsemals are weak, while 

 the ribs are strong. The caudal peduncle is exceedingly stout, nearly 

 equalling the body. Eadii : D. 10 ; A. 9 ; V. 6. Vertebrae : D. 14, four 

 anterior to first interneural; 0. 13. The scales are too attenuated to be 

 counted. It is quite possible that this species possesses an adipose dor- 

 sal fin, in which case its present generic reference must be abandoned. 

 Better specimens only can solve this question. 



