152 KANSAS UNIVERSITY SCIENCE BULLETIN. 



The only other Conocardium that I know of occurring in the 

 Permian is found in the valley of Palermo, and belongs to a 

 decidedly older horizon. It is a very different form from ours. 



CYRTODONTARCA Jak. 



So far as observed, our fossils from the Red Beds do not 

 have the vertical cartilage pits on the area, as figured by 

 King for Bakewellia, and, instead, seem to show only hori- 

 zontal striations. The dentition seems to be somewhat simi- 

 lar in both genera. Our specimens are referred to CyHodon- 

 tarca. 



CYRTODONTARCA ? GOULDII Beede. 



Plate VI, figures 1-le. 



Bakewellia gouldii Beede. Inv. Pal. Red Beds, p. 5, pi. I, figs. 2-2c, 1902. 



Shell of moderate size, aviculiform, compressed, thin, con- 

 siderably longer than the hinge. Beaks low, subterminal ; 

 umbonal ridge well defined. Anterior ear nearly obsolete ; 

 posterior one alate, not sharply separated from the body of 

 the shell. Border sinus very shallow, anterior margin rather 

 sharply and regularly rounded, ventral margin gently curved 

 posteriorly and nearly straight in front, rounding abruptly 

 to the end of the hinge. There is rarely any indication of a 

 sinus in the adult left valve, though slight ones are some- 

 times seen in the younger specimens. There is usually a 

 slight'depression extending from the front of the beak a little 

 obliquely backward nearly to the margin of the shell. The 

 hinge of the left valve is armed behind with one lamellar 

 tooth which is nearly parallel to it, and the anterior part 

 with a rather complex dentition. There are two diagonal 

 teeth beneath the beak, lying about parallel with the axis of 

 the umbonal ridge ; in front of these is a third tooth, curved 

 forward and enlarged to twice or three times the size of the 

 others. Connecting with the lower end of this enlargement 

 there is a ridge extending as a buttress downward behind 

 what appears to be a semiobsolete muscular impression, 

 somewhat as in the PUurophori, though much less marked. 

 Sometimes there seems to be a very slight, thin tooth in 

 front of this scar. There is a strong muscular impression in 

 front of the beak to the rear of the buttress. This scar, as 



