NO. 1312. SYNOPSIS OF THE VENERID.E—DALL. 363 



Valves oblong, subcompressed, vertically expanding and subangular 

 on the posterior dorsal margin; lunule set off by an incised line, the 

 escutcheon defined by a carina, both long and narrow; surface concen- 

 tricall}" grooved; internal mai'gius smooth; pallial sinus ample, hori- 

 zontal, free below, rounded in front; the posterior right and two ante- 

 rior left cardinals bifid or grooved; colors lively, often with a dark 

 Uneated pattern on a paler ground. 



Tropical and temperate waters of the Old World. Paremhola Romer, 

 isST, is synonymous. 



Section Tapes Megerle s. s. (See above.) 



Section PoUtitapes Chiamenti, 1900. Type, Vemts aurea Gmelin. 



Valves oldong, plump, not angular above, behind; surface with fine 

 concentric sculpture and obscure radial striation; lunule .small, cir- 

 cumscribed, escutcheon not defined; pidlial sinus short, ascending, free 

 below, rounded in front; color delicate and variable. 



The siphons arc united for three-fourths of their length in T. virgin- 

 eus which is not known to form a byssus. The group is Tapes Sacco, 

 1900, not Megerle, 1811. 



Section PuUmtra Sowerby, 1826. Type, Venus pullastra Montagu. 



Shell oblong, tumid, blunt behind; valves finely reticulately sculp- 

 tured, with hardly differentiated lunule or escutcheon; the latter nearly 

 linear; inner margins entire; pallial sinus deep, ample, horizontal, 

 rounded in front and confluent with the pallial line below; the two pos- 

 terior right and middle left cardinals are bifid; coloration feeble. The 

 siphons are three-fourths united in the typical species. 



Section 3£yrsus H. and A. Adams, 1858. Type, Ta2)es corrugatus 

 Deshaj^es. 



Valves as in Pullastra, but the concentric sculpture is broken and 

 corrugated, the shell more elongate, though, from its nestling habit, 

 very variable in outline; teeth as in Ptdlastra, lunule obscure or not 

 defined, the escutcheon with a feebly carinate margin; pallial sinus 

 small, slightly ascending, free below and rounded in front; inner 

 margins smooth; coloration dull and unattractive. 



This is Metis Adams, 1857, not 1856; Myrsopsis {pernarum Bonelli) 

 Sacco, 1900, from the Italian Tertiaries, differs but slightly. 



Subgenus Ruditapes Chiamenti, 1900. Type, Venus decussata Lm- 



na3us. 



Valves convex, oblong; surface dull and feebly colored; sculpture 

 strong distally, more or less reticulate, the concentric ridges inosculat- 

 ing anteriorly and feeble on the middle of the disk; the radial sculp- 

 ture stronger; inner margins smooth; pallial sinus large, free below, 

 horizontal, rounded in front; lunule circumscribed, the escutcheon 

 feebly defined; all the inner cardinals more or le.ss bifid; the siphons 

 wholly free from each other and a byssus present. 

 Proc. N. M. vol. xxvi— 02 25 



