NO. 2331. WEST AMERICAN MOLLVSKS—BARTSCH. 167 



as in Rissoa, and not so slender. The operculigerous lobe is small, very little 

 alated anteriorly, but expands below into a dark, flat, arcuated niembrance ; 

 no cirrhus is visible, and I believe none exists; it carries a strong, red-brown, 

 suboval, testaceous operculum, sharp above, rounded below and at the outer 

 edge, and straighter on the columellar side. The structure of the fine stria 

 on the upper surface is of subannular figure, with a longitudinal furrow about 

 the middle, which forms a raised rib on the under part, the whole of that 

 area being thick, coarse, and irregular, with, at the nucleus (which is nearer 

 the base than the center) a testaceous apophysis, more prominent than in 

 Jeffreysia and stronger and longer; indeed, as much as in some of the 

 Chemnitzia. 



These animals inhabit the lower littoral levels at Penzance ; their locomotion 

 is deliberate, and they evince considerable shyness. There are many fasciated 

 varieties and a white one. 



An examination under high magnification of the genotype and the 

 West American material permits me to add that the nepionic whorls 

 are finely thimble pitted. 



Only four species and a variety, the latter without real status, have 

 prior to this been reported from the West Coast of America. The 

 first two of these were described by Philip P. Carpenter in 1856, on 

 pages 361 and 362 of the Catalogue of Mazatlan Shells, under the 

 names of Eydrohia uT/va ? Pennant and Jeffreysia alderi, while the 

 rest: Barleeia subtenuis, Barleeia {? subtenuis, \^y.) rimata and 

 Barleeia haliotiphila, were christened by the same author in 1864 in 

 the 1863 Report of the British Association for the Advancement of 

 Science, the first name replacing Ilydrobia ulva f of the Mazatlan 

 Catalogue. In 1870 de Folin added a fourth species, Rissoa foly- 

 chroma, in volume 1 of his Fonds de la Mer (p. 133, pi. 20, fig, 5). 



The large amount of material that has accumulated in the collec- 

 tion of the United States National Museum not only enables one to 

 more clearly define the range of distribution of the known forms, but 

 also makes it necessary to describe a number of additional species. 



KEY TO THE WEST AMERICAN BARLEKIAS. 



Periphery of the last whorl acutely carinated : 



Altitude about 4 mm dalli. 



Altitude about 2 mm bentleyi. 



Periphery of the last whorl not acutely carinated : 

 Periphery of the last whorl obsoletely carinated : 

 Shell unicolor : 



Shell broadly conic 



Whorls coarsely spirally striate subtenuis. 



Whorls finely spirally striate sanjuanensis. 



Shell narrowly conic: 



Altitude about 3.2 mm oldroydi. 



Altitude about 2.5 mm halioHphila. 



Shell banded : 



Whorls strongly inflated polychroma. 



Whorls not strongly inflated californica. 



