FOSSILS OF THE DEVONIAN. 



193 



Bellerophon perplexa, n. sp. 

 Plate xvii, figs. 6, (i a, &. 



Shell subglobose, the transverse and lateral diameters being 27 mm and 

 33 mm , respectively, in a medium-sized specimen. Volutions five or six, 

 broadly rounded on the dorsum, subangular on the dorso-lateral angle of 

 each volution, and sloping rapidly into the broad, open umbilicius from the 

 dorso-lateral angle. Each volution embraces the dorsal surface of the pre- 

 ceding, leaving the entire umbilical slope of each exposed. The extreme 

 transverse section of each volution is equal to four times the lateral section 

 as it is measured midway, or at the carina. The aperture is probably sim- 

 ilar in form to the transverse section of the last volution, as in a number of 

 examples examined no evidence of any expansion was observed. The dor- 

 sum has a narrow, well-defined carina. 



Test varying in thickness from .75 mm to 1.50 mm , with the variation in 

 the size of the shell. 



Surface marked by strong striae; originating on the inner margin of the 

 umbilical lobe they cross it obliquely, curving slightly and extending back- 

 ward at an angle of 45 to the dorso-lateral angle over which they curve, 

 retaining a backward slope of 15 to the dorsal carina. 



The largest specimen in the collection has a transverse diameter of 

 50 mm . The test is removed from the outer portion of the last volution, the 

 mold retaining only the slight dorsal carina, a feature that in another speci- 

 men is obsolete ; this, however, is rarely the case as in most examples it 

 occurs on the outer volution and may be traced on breaking away the 

 volutions to the second or third, where the transverse diameter is five mil- 

 limeters. 



Formation and localities. Lower horizon of the Devonian limestone, 

 Comb's Peak, Gray's Canon and Atrypa Peak, Eureka District, Nevada. 



Bellerophon Combsi, n. sp. 

 Plate xvii, figs. 9, 9 a, I. 



Form large, robust, subglobose; exterior shell unknown. In the cast 

 the body volution is large, nearly if not quite concealing the inner volu- 

 tions; broadly rounded on the dorsum and gradually expanding towards 

 13 c D \v 



