HOLOSPIRA. 73 



more or less perfectly. With the exception of H. goldfussi 

 all are species of great rarity. Another form, H. teres Mke. 

 (sp. no. 28), unknown internally, may prove to belong to this 

 group. All of them are much alike in the internal armature. 

 They may be briefly diagnosed as follows : 



//. tetrelasmus: Length 13.8-14.8, diam. 4.5-4.6 mm., being 

 thus about 3 times as long as wide; whorls 12i/o-13 1 /4, sculp- 

 tured with white or whitish riblets on a fleshy ground, the top 

 and base opaque white. The columellar lamella runs nearly 

 or quite to the mouth. Mexico. 



H. pilocerei: Length 14, diam. 3 l / 3 mm., being about 4 times 

 as long as wide; whorls 15, finely striate, the last rugulose, 

 protracted. Interior unknown. Mexico. 



H. goldfussi: Length 11-15, diam. 3.5-3.6 mm.; whorls 12- 

 14V:>, rather strongly ribbed, the ribs the same color as the 

 dull fleshy intervals. Internal column cylindrical, not wider 

 above; columellar lamella barely entering the last whorl. 

 Texas. 



H. goniostoma: Length 15, diam. 3.7, the length about 4 

 times the diameter; whorls 15-16, sculptured with fine white 

 riblets. Internal column decidedly wider above; columellar 

 lamella obsolete in the last whorl. Mexico. 



H. pfeifferi: Length 15.5-17.5, diam. 5-5.6 mm., about 3 

 times as long as wide; whorls 12, very finely sharply ribbed. 

 Palatal lamella wanting, basal lamella small. Tehuacan, 

 State of Puebla. 



H. nelsoni: Length 16-17.4, diam. 4.7-4.5 mm., whorls 15y 2 . 

 White, with blue stains and flecks, the early whorls fleshy- 

 brown; slowly tapering, more rapidly near the apex, where it 

 is sharply, finely striate, the following whorls obsoletely ribbed, 

 last whorl finely and distinctly ribbed; ribs and intervals of 

 the same color. Internal column small, cylindrical, of about 

 equal width above and below. Guadalupe Mts., Mexico. 



1. H. TETRELASMUS n. n. PL 21, figs. 23-27. 



This species shows externally some resemblance to H. tryoni, 

 but the shell terminates in a longer cone above, and the chalky 

 white color is confined to the upper and lower portions, while 



