COPE ON ICHTHYIC FAUNA OP THE GREEN EIVER SHALES. 811 



dorsal scuta are furnished in tUe D. ]}ectorosus with an especially 

 prominent median keel. 



Measuremenis. 



M. 



Total length O.OtO 



Length (axial) tohelowD. I 0.03:^ 



Length (axial) to above A. 1 0.043 



Length (axial) to base of caudal fin 0.070 



Length of head 0.022 



Depth at orbit , 0.017 



Depth at pectoral fin 0.026 



Depth at dorsal fin , .' 0.024 



Depth at caudal peduncle 0.008 



This species is represented by several specimens. 



DiPLOMYSTUS HUMiLis, Leidy. 



Clupea 7tii}?u7(s, Leidy, Final Report U. S. Geol. Surv. Terr, i, p. lO.'S, pi. xvii, 

 hg- 1- 



This and the following species, already referred to a distinct section 

 of the genns Dijtlomysfus, differ from those above described in several 

 points. They have a much shorter anal fin, and the caudal part of the 

 vertebral column is thus shorter. The anterior neural spines do no pre- 

 sent the antero-posterior laminar expansion. The ventral fin commences 

 a little behind the origin of the dorsal. The formulae for the D.liumilis-a.Te 

 as follows :— Eadii : D. I— 11 ; A. 1—14. Yertebrte : D. 21 ; C. 13. Depth 

 to length as 3 : 8. 5. The Biplomystiis tlieta {Clupea tJieta Cope, Ann. 

 Eep. U. S. Geol. Surv. Terr. 1873, p. 461) is intermediate between the 

 species of the two sections in the structure of its anal fin, which includes 

 twenty-six rays. 



As at the Green Eiver locality, so at this one, this Herring is the most 

 abundant species. One-third the entire number of specimens are refer- 

 able to it. • 



DiPLOMYSTiTS ALTUS, Leidy. 



Clupea alta, Leidy, lov. cit. p. 196, pi. xvii, fig. 2. 



Also abundant. Formulae : — Eadii : D. 1. 11 ; A. 1. 13-15, Vertcbrre : 

 D. 225 C. 12. Depth to length (without caudal fin) as 4:8. 



Erismatopterus endlichi, s2). nov. 



This fish displays the characters of the genus to which it is referred, 

 and of which a description will be found in the Annual Eeport of the 

 United States Geological Survey of the Terri tories for 1870, p. 427. The 

 ventral fins are neither abdominal nor pectoral, but intermediate, and the 

 dorsal fin is above the abdomen. Both it and the anal are short, and 

 are supported in front by two or three strong appressed spines. The 

 vertebra} are hourglass-shaped, and the scales cycloid. The ventral 

 rays are seven in num ber in E. cndlkld and E. riclseclcri. 



