THE NAUTILUS. 41 



Beak sculpture distinctly double-looped, consisting of three to 

 four bars, the first one or two bars subconcentric. According 

 to the soft parts, this genus belongs in the group of Lampdlinae 

 which have a differentiated mantle edge in front of the bran- 

 chial; but with regard to the particular structure of this edge, 

 it is unique, in having papillae as well as a short, elevated la- 

 mella. It is not very closely allied to Lampsilis, which has a 

 large and long mantle flap, but stands nearer to the Eurynia- 

 type, and possibly most closely to Carunculina (recte: Toxolasma 

 Raf. ), and we might regard the short lamella of Lemiox as an- 

 alogous (or possibly even homologous) to the "caruncle" of 

 Carunculina. But it cannot be united with the latter on account 

 of the shape of the lamella, and the sculpture of shell and beaks 

 (it differs also by the nearly complete connection of the inner 

 lamina of the inner gills). 



Simpson placed the species with Micromya (now a subgenus 

 of Eurynia), but the structure of the mantle edge as well as the 

 shell is distinctly different. 



There is no question that this form should be regarded as the 

 representative of a distinct generic type, Lemiox, and that it 

 should be placed in the vicinity of Eurynia and Toxolasma 

 ( Carunculina'). 



In the denticulations of the edge of the shell, there is some 

 resemblance to the genus Truncilla, but there is no considerable 

 space between the edges of the mantle, as in that genus, and 

 also in other characters, Lemiox is entirely different from Trun- 

 cilla. 



NEW SUBSPECIES OF VIVIFARUS AND CAMPELOMA. 



BY H. A. PILSBRY. 



VlVIPARUS CONTECTOIDES IMPOLITUS n. Sllbsp. 



The shell is heavier than contectoides, rough and with irregular 

 growth-lines and wrinkles, and often somewhat malleated ; 

 shoulder more conspicuous ; and on the last whorl the bands 

 are obsolete. The umbilical perforation is very narrow or 

 closed. Length 39, diam. 31.5 mm. Type no. 66701 A. N. 



