8 BULLETIN 68, UNITED STATES NATIONAL MUSEUM. 



the outer lip frequently internally lirate; in the larger forms the 

 aperture is obscurely channeled in front; the larval shell is sinistral 

 the adult dextral, the former frequently set at an angle to the adult 

 axis, or more or less immersed in the adult apical whorls; it is usually 

 helicoid and smooth; the sculpture varies from nothing to ribbed, 

 spirally sulcate or reticulate; the coloration when present usually 

 reddish, brownish or yellow. The eggs are numerous and depos- 

 ited in a lenticular mass. The distribution is world-wide, but the 

 larger forms are mostly tropical. 



SYNOPSIS OF THE GENERA, SUBGENERA, AND SECTIONS. 



SYNOPSIS OP THE GENERA. 



Genus PYRAMIDELLA Lamarck. 



Shell elongate-conic, whorls usually inflated and regularly increasing; the pillar 

 with from one to three folds; the outer lip entire; the shell usually larger than in 

 Turbonilla. 



Type. — Trochus dolabratus Linnseus. 



Genus TURBONILLA Risso. 



Shell cylindro-conic, many whorled, generally slender; columellar fold single, 

 varying in strength, outer lip entire; shell usually smaller than in Pyramidella and 

 larger than in Odostomia. 



Type. — Turbonilla typica Dall and 'BaTtsch=^ Turbonilla plicatula Risso, not Turbo 

 plicatulus Scacchi. 



Genus ODOSTOMIA Fleming. 



Shell usually short, few whorled, subconic or ovate; columellar fold single, vary- 

 ing in strength, outer lip entire. 

 Type. — Turbo plicatus Montague. 



Genus MURCHISONELLA Morch. 



Shell minute, cylindro-conic; outer lip with an anal sinus behind the jjeriphery 

 of the whorl; pillar with the plait obsolete or internal, whorls numerous and inflated. 

 Type. — Murchisonella spectrum Morch. 



KEY TO THE SUBGENERA OF PYRAMIDELLA. ^ 



A* Columellar folds three. 

 Shell umbilicated. 



Basal fasciole absent, surface polished, marked by extremely faint lines of 

 growth and microscopic spiral striations. 



Subgenus Pyramidella Lamarck, s. s., 1799 (p. 19). 

 Type, Trochus dolabratus Linnaeus. 



Basal fasciole present, surface less polished than in Pyramidella s. s., marked 

 by lines of growth and microscopic spiral striations. 



Subgenus Milda Dall and Bartsch, 1904 (1). 

 Type, Obeliscus ventricosus Quoy. 



o In order to keep the key in its present compact form we have placed all references 

 to citations and synonyms at the end of the key. The numbers in brackets (1-45) 

 following the names refer to the citations. 



