394 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



pterygoids are narrow. The supraoccipital process is long. Front nearly 

 plane transversely. The mandibular ramus is of uniform depth from 

 the coronoid forward, and the symphysis is subvertical. The inner 

 alveolar edge extends almost to the symphysis. 



Measurements. m. 



Length of cranium 0.115 



Width of cranium at quadrates 0.080 



Interorbital width of cranium .• 0.019 



Greatest width of palatal fossa 0.036 



Elevation of occiput 0.033 



Length of mandible 0.075 



Depth of mandible at symphysis 0.019 



Length of plastron 0.615 



Width at axillae 0.360 



Width at inguinal borders 0.310 



Width between posterior apices ^ 0.100 



Width at base of anterior lip 0.125 



Width at end of anterior lip 0.070 



Length of anterior lip above 0.100 



Length of an anterior marginal bone , 0.075 



Width of the same O.IGO 



Thickness of the same 0.034 



Length of femur (condyles estimated) - 0.170 



Width of head plus great trochanter 0.090 



Diameter of head - 0.045 



Diameter of shaft (least) 0.030 



Xeeobates cyclopygius, sp. nov. 



This species was found by C. H. Sternberg in the horizon in which the 

 preceding species was obtained. It resembles it in several important 

 features; but as the skull is unknown, it is not certain that it belongs to 

 the genus Xerobates. 



The general form is round, the carapace being shortened behind, where 

 its outline is a segment of a circle. The posterior marginal bones are 

 vertical, and the edges are shortly recurved from one inguinal notch to 

 the other. It resembles the X orthopygius in the low buttresses which 

 connect the base of the costal bones with the elevated inguinal margin 

 of the hyposternal bone. The axillary margin of the hyosternal is not 

 elevated. The posterior extremity of the plastron is openly notched. 

 The anterior lip is unknown. 



The carapace is flattened, but has a low tuberosity on the posterior 

 part of the first vertebral scutum. In front of this, the superior surface 

 descends to be again produced into the transverse flaring anterior lip- 

 like border. The surface of the costal bones is marked by grooves con- 

 centric with the border of the carapace, which are separated by obtuse 

 intervals wider than themselves. The plastron is marked by grooves 

 parallel with the longitudinal and transverse sutures. 



The scuta are well marked. The pectoral is very narrow. The nuchal 



