810 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 
contains thirteen rays. The greatest depth is at the pectoral region, the 
outlines contracting to the base of the anal fin. The dorsal outline is 
convex. The profile descends gently. The muzzle is half as long as the 
diameter of the orbit, which enters the length of the head three times. 
The latter enters the length without the caudal fin three and three- 
fourths times. There is a row of short, conical teeth along the middle line 
of the mouth, which is not on the vomer, but is on the parasphenoid or 
axial hygal bones. Similar teeth exist in the mouth of D. dentatus. 
The jaws may be furnished with minute teeth, or they may be wanting. 
The scales are thin and difficult to count; there are fifteen rows between 
the vertebral column and the anterior anal rays. 
Measurements. 
M. 
oval On shh: 2 sss d Sienna see Pasa eine comic tiwewes deeeeetnaaeoume aeoseeaes 0,195 
en Gth OF NEA sc sce-schoas scceweweajow ees eemcimmscemenines ae ence nee edaeaeaee 0,040 
' Axial length to below first dorsal ray.............-- etinmea trend Bacameemeema cs 0.073 
Axial length to above first anal ray ..--.. -22. 2-2 eee cane eee duigmiiihacied eeut 0.092 
Axial length to base of external caudal rays... ..----. 2222 eee eee eee e eee ee 0.149 
Depth: at orbltsaccstgccusgetesae ctecis sind wwe cine dieitae ne aa ae seine SE eee te cee 0.030 
Depth atiocciputiscnces cesses tesesvscnsvia occa samsewasnmen’s 4s caus ewes egeeee 0.044 
Depth at first dorsalray...--.... sere Me nome Seki tae se-ammnism ate some eee wecRetnes 9.047 
Depth. middle anal Tay s.cosiwisvewe acess tee ete oscsaccecesbtscoseneetceke 0.027 
Depthat base-of Caudal fit cca ce see eeedsencSeennasse Siedheesccseceweeneet 0.016 
This Herring is represented by a great numBer of well-preserved spe- 
cimens, and was, next to the D. humilis, the most abundant fish of the 
waters of the ancient Green River lake-basin. It is distinguished from 
the D. dentatus by the larger number of anal and smaller number of 
dorsal radii, and by the shorter head and relatively more slender body. 
The specimen measured represents the average size; the largest ob- 
tained is half as large again, and much smaller than the type of D. den- 
tatus. 
DIPLOMYSTUS PECTOROSUS, Cope, sp. nov. 
This Clupeoid is represented by small specimens of a deeper form: 
than that seen in the two preceding species. It is also characterized by 
a smaller number of dorsal radii than either of them. Formula: D. I. 
8-9; A. I. 40-44. Vertebre: dorsal, 16-17; caudal, 22. The greatest 
depth is in the pectoral region, and enters the length minus the caudal 
fin a little less than three times. The outlines contract from the ventral 
fins, and the anal region is longer than the abdominal. The eye isa 
little more than one-fourth the length of the head, and the latter enters 
the total minus the caudal fin three and a half times.’ The ventral fins 
are small, and commence well in advance of the line of the dorsal. The 
last dorsal ray is nearly above the first anal; the caudal is deeply 
forked. As in the two preceding species, the neural spines in front of 
the interneurals present a laminar antero-posterior expansion. The 
