Section Propeamusiiim de G-re^^orio. 



PECTEL' (P?.0?::i\I-,IU3IUlvI) 3PEKDULUS n. sp. 



DesgriT)tion »- Shell small, thin, com-oressed, suhorbio-ular, 

 higher than '.'.'ide ; dorsal r.iareins with a steep slope; external 

 surface of left valve scxilptnred with very fine concentric striae, 

 obsolete toward the ventral niarp-in, mth faint suggestions of a 

 feV' coarser, more wideljr spaced co.icenti'ic lines near the ventral 

 margin; dorsal Valf of the shell hearing exceedingly fine radial 

 striae, barely visible imder the microscope; the entire surface 

 covered with camptonectes strictions; internal lirae faintly visi- 

 ble from the exterior; airricles small, with a median broad ridge, 

 separate-^ from the disk by a scarcely impressed line; interior with 

 ten prominent, relatively heavy lirae, extending about half the 

 distance to the umbo, thickened toward the ventral mar~in, but 

 terminating before the margin is reached; distal extremities of 

 the lirae acute, except the two nearest the dorsal mars-in, which 

 are roimded; right vslve not kniwn. 



Dimensions .- lat., 5.8 mm.; alt., 6.1 rnr:!. 



RemarVs . - It is somewhat surprising to fine this delicate 

 shell in the Bov'den marl. It bears a r^-^markable close resemblance 

 to P. pourtalesianus Dall 1), one of the most common of the deep- 



