PERCOMORPHI. 81 



column, probably two rows concealed by it. The caudal peduncle is 

 but little contracted. Length from scapular arch to extremity of caudal, 

 ".0335; depth at origin dorsal fin, ".008. 



Measurements. 



u. 



Total length No. 2 055 



Length of cranium '. 013 



Length to basis D. I 0232 



Length tobasisA. I 033 



Length to basis V. I 0205 



Length to basis caudal - 0466 



Depth at D. I 01 



Depth of caudal peduncle 0058 



There are many individuals on the slabs of Green River slate, some of 

 them perfectly preserved. Many of these slabs represent that portion of 

 the stratum which is highly carbonaceous, portions of it thrown into the 

 fire burning freely. Dr. Hayden, who has brought numerous specimens 

 from this locality, informs me that the laminae exhibit greater numbers of 

 these little fishes. No doubt the carbonaceous character of the shales is 

 due to the decomposition of their bodies. The nature of the deposit, and 

 mode of preservation, remind one strongly of the Cyprinodon meyeri of 

 Agassiz, from the neighborhood of Frankfort-on-the-Main. That species 

 dififers specifically in presenting 18 anal radii. 



Some of the specimens above described were obtained from the Green 

 River Cut, and preserved for scientific study, by L. E. Ricksecker. 



Erismatopterus eickseckeri Cope. 



Annual Report U. S. Geol. Surv. Terrs., 1870, p. 427. 

 Plate VI, fig. 2. 



Length, three to four inches; head large. Vertebrae: D. 13 ; C. 1(J; r= 



29, ten between the intemeural bone supporting the first dorsal ray, and the 



first interhsemal supporting the first anal ray. There are only seven in 



this position in E. levatus. Anterior dorsal ray anterior to the point half 



way between end of muzzle and end of vertebral column. Branchiostegal 



radii fin distinguishable. Head stout, mouth terminal, orbit equal length 



of muzzle; maxilliarv bone reaching line of middle of orbit. Scales 

 6 o 



