66 THE WASATCH AND BEIDGER FAUN^. 



is a similar production on the posterior side for a similar purpose. The 

 basis of the spine proper is smaller than that of the pectoral, and is about 

 as wide as deep. 



In a number of fragments of another indi\ndual found together, the 

 basioccipital has the characters already described. The dentary bone is 

 curved inward, and is acute below, widening regularly to the alveolar 

 border. There is no groove on the inner face, while the outer is striate- 

 grooved and has a series of pits along its lower middle. 



Measurements. 



It 



Diameter occipital articnlation 009 



Width alveolar face. 004 



Depth ramus at middle 008 



A part of the operculum of a third individual (with similar spines) 

 displays great rugosity and elevated radiating ridges; length of articular 

 cup ".OOGS. 



The specimens are chiefly from the bad lands of the Upper Green River. 



Rhineastes aecuatus Cope. 



Plata V, fig. 12. 



Annnal Report U. 8. Geol. Snrv. Terra., I^f72 (1873), p. C41. Pimelodus antiquus Leidy, Final Report IT. 

 S. Geol. Siirv. Terw., i, 1873, p. 193, PI. xvii, figs. 9, 10. Proceedings Academy Phila., 1873, p. 

 99, name only. 



There are numerous spines about the size of those of the last species, 

 which differ in the want of the fine serrated anterior edge. I select one aa 

 the type, wliich belonged to the pectoral fin of the right side. It is 

 unbroken, and is curved from base to apex. The latter is acute by an 

 oblique posterior truncation. The surface is strongly striate and the teeth 

 of the posterior edge are closely set ; the proximal point distally, the distal 

 proxiniall}-. In this specimen there is a trace of anterior serration ; in 

 many specimens none whatever. The external surfaces of the epiclavicular 

 and coracoid bones are strongly rugose-striate, as is the case in all the 

 species of this genus, and the most characteristic fragment is that portion 

 of the scapular arch at the base of the pectoral spine. 



Measurements. 



u. 



Length of Hpinc on riin'c 052 



Dianii'tcr at liane; long 006 



Diameter at banc ; iihort 004 



