49 Olsson, Neocene Fossils ii 



dula Dall and T. greensboroense Martin the species may be distin- 

 guished by its lack of the carina which occurs on the periphery 

 of those shells. It is probable • that H. C. Lea's Delphinula 

 oblique- striata belongs in this genus. This last-mentioned species 

 has the radiating ribs divided into 2 or 3 branches near the peri- 

 phery, with the umbilicus bordered by a slight, carinated line. 

 Yorktown formation ; Yorktowfi, Vd. 



Pecten (Pecten) smithi, n.sp., Plate 4, Fig's i, 2 



Left valve small, thin, flat with a slight depression at the 

 beak ; shape ovate, as high as broad ; ribs about 20 to 22 in num- 

 ber, low and separated by flat interspaces, about twice as wide as 

 the ribs ; ribs becoming obsolete on the anterior submargin (and 

 probably also on the posterior) and are here replaced by a rather 

 prominent ridge ; ribs and interspaces at first crossed by concen- 

 tric lamellose lines, which also pass over the submargins and on- 

 to the ears ; these concentric lines are equally spaced and the lam- 

 ellae appear to have been originally roof-like, passing from one 

 line to the other ; this concentric sculpture is developed for a time 

 and then suddenly ceases, the remainder of the shell having only 

 the ribs ; interior of shell smooth, lirated by the ribs. 

 Height 26, apparent width 29 mm. 



The above description is based on two imperfect left valves. 

 Both are from Kingsmill, Virginia. On the smaller shell, the con- 

 centric lines cover the entire shell. On the larger this sculpture 

 is lacking from the basal part, having disappeared suddenly at a 

 time when the shell had reached the same size as the smaller shell. 



Yorktozvn formation; Kingsmill, Va. 



Pecten (Nodopecten) vaccamavensis, n. sp. Plate 1, Fig. 1 



Shell rather large ; valves of moderate but equal convexity ; 

 left valve with about seven narrow, elevated ribs which are slight- 

 ly nodose at more or less equal radial distances from the beak ; 

 interspaces very wide and with about 4 or 5 longitudinal lines 

 which are made slightly setose by the equi-distant, elevated, con- 

 centric lines ; anterior and posterior marginal slopes, abrupt ; ears 

 flat, with narrow riblets, slightly imbricated by the concentric 



