36 GASTROCOPTA, NORTH AMERICA, WEST INDIES. 



they have the appearance of young or half grown of some 

 other species, and probably were overlooked, partly due to 

 the habit of most Bifidarias of this group of covering their 

 shells with dirt" (Sterki). 



The type and only perfect specimen found is figured. It 

 appears to be distinct from pentodon and tappaniana, but in 

 so variable a group further specimens are required for a full 

 understanding of its relation to known species. 



7. GASTROCOPTA PILSBRYANA (Sterki). PI. 3, figs. 10, 11, 12. 



"Shell minute, narrowly perforate, cylindrical-oblong to 

 cylindrical, somewhat attenuated towards the rather blunt 

 apex; colorless (when fresh glassy), with a very delicate 

 bluish tint; smooth and polished, with few, irregular, micro- 

 scopic striae which are more marked near the aperture. 

 Whorls 43/2 to 53/2> moderately rounded with a rather deep 

 suture, especially in the upper half, regularly and slowly in- 

 creasing, the embryonal being relatively large, the last some- 

 what ascending toward the aperture; the latter of moderate 

 size, lateral, subovate, margins approached; peristome some- 

 what expanded, without a thickened lip or a callous in the 

 palatal wall; outside is a barely perceptible trace of a crest 

 near the margin, and behind that a slight impression most 

 marked upon the inferior palatal fold. Lamellae 4 or 5 : one 

 apertural [parietal], rather high, of moderate length, simple; 

 one columellar, horizontal, of moderate size, simple; basal 

 very small or wanting; palatals the typical, inferior deeper- 

 seated, of moderate size, superior small or very small. Alt. 

 1.5 to 1.7, diam. 0.8 to 0.9 mm." (Sterki). 



New Mexico: Gallup, McKinley Co.; Sulphur Springs, 

 near Jemez, Bernallilo Co. (Ashmun) ; Santa Fe (Ashmun), 

 and Sandia Mts. (Maud Ellis), Santa Fe Co.; Las Vegas and 

 Pecos, San Miguel Co. (Cockerell) ; Duran, Torrance Co. 

 (Pilsbry) ; San Rafael (Ashmun) and Grant (Pilsbry & 

 Ferriss), Valencia Co.; Black Range, Socorro and Sierra 

 counties (Pilsbry & Ferriss) Sierra Blaiica and Capitan 

 Mts., Lincoln Co. (Ashmun) ; Cloudcroft, Sacramento Mts., 

 Otero Co. (Viereck) ; Dripping Spring, Organ Mts., Dona 



