LOWER CARBONIFEROUS FOSSILS. 543 



of Soda Butte Creek, northwest of Abiathar Peak, Absaroka Range, a 

 locality which has already furnished several new species, and seems to 

 possess a somewhat distinct local fauna. 



Camarotcechia sp. consists of a single dorsal valve. The shape is 

 slightly oval, length and width about equal; curvature of the outline regu- 

 lar, and not angular where the anterior margin meets the lateral slopes. 

 Extremely gibbous, the thickness of the valve being more than half the 

 length or width. Fold not very high, but defined to the vicinity of the 

 beaks. It is marked by five rounded plications, and a like number are to 

 be found on the two sides. 



This form seems to be related to C. orbicularis, of Chemung age. 



Formation and locality: Madison limestone, limestone bluff south 

 side of Soda Butte Creek, northwest of Abiathar Peak, Absaroka Range; 

 J. P. Iddings. 



LIORHYNCHUS Hall, 1860. 



LlORHYNCHUS HAGUEI 11. sp. 

 PI. LXIX, figs. 5«, 56. 



Shell rather large, tumid. Ventral valve flat in effect ; subquadrate in 

 outline ; beak strongly incurved ; fold deep. Thus the anterior and posterior 

 angles of the quadrate shell are strongly flexed in one direction, while the 

 lateral angles are prominently elevated. Dorsal valve very rotund ; fold 

 high ; sides strongly recurved. The surface is smooth (?), sometimes show- 

 ing varices of growth. Fold and sinus alone plicate. Striae on the sides 

 of the shell entirely obsolete. There are five plications on the fold, neither 

 sharp nor strong. The central three are slightly larger than the lateral 

 ones, which are not defined on the outer side, but lie in the regular curva- 

 ture of the shell. Four nearly obsolete plications in the sinus. 



The general appearance of the shell suggests the genus Pugnax, but a 

 reference to that type is impossible by reason of internal structures. A 

 section across both valves near the beak shows that the dorsal valve is 

 provided with a well-developed median septum, and that the ventral valve 

 has two converging laminar plates in the rostral region. 



Liorhynclms liaguei is very close to L. greenianum Ulrich, of Keokuk (?) 

 age, from New Albany, Indiana, but the latter has three coarse plications 



