SPIRAXIS. 25 



irregular riblets, diaphanous, waxy-hyaline. Spire regularly 

 tapering, rather acute. Whorls 7, a little convex, the last 

 two-sevenths the length, rounded basally. Columella rather 

 straightened, thread-like. Aperture slightly oblique, oblong; 

 peristome sample, unexpanded, with subparallel margins, the 

 columeHar margin sample. Length 7.5, diam. 2.5, aperture 

 2x1 mm. (P/V.). 



Mexico: Cordova, State of Vena Cruz (Salle). 



Bulimus costatostriatus PFR., P. Z. S. 1856, p. 319; Monogr. 

 iv, 460. not Opeas c., Crosse et Fisch., Moll. Mex. p. 598, pi. 

 26, f. 5. 



This form differs from Opeas beckianum, 0. micro, etc. by 

 its imperforate axis and thread-like columella. It has not 

 been figured, and ite relationships with the numerous Spiraxes 

 and Pseudosubulinge of East Mexico remain to be worked out. 

 0. costatostriatus of Crosse and Fischer is apparently a form 

 of 0. micra, and not in my opinion the true costatostriatus of 

 Pfeiffer, which will prove to belong, I think, to Volutaxis or 

 Pseudosubulina. 



21. S. ODIOSUS (Pilsbry). PL 2, figs. 19, 20. 



Shell slender, turrite, completely imperforate, corneous, 

 sufficiently translucent to show the columella faintly through. 

 Surface glossy, irregularly scored by unequally spaced longi- 

 tudinal grooves and some slight wrinkles. General outlines 

 of the spire straight; apex obtuse. "Whorls 8y 2 , the earlier 

 strongly convex, the last two slightly flattened. Aperture 

 ovate; outer lip than, moderately arched forward, .columella 

 concave, forming a distinct angle with the parietal wall. Alt. 

 7.1, diam. 2, longest axis of aperture 1.8 mm. 



Mexico: Patzcuaro, State of Michoacan (Khoads). 



Opeas odiosum PILS., Proc. A. N. S. Phila. 1899, p. 399; 

 1903, p. 775, pi. 50, f. 3. 



The impressed, widely-spaced grooves are similar in char- 

 acter to those of Vitrea indentata Say. It is related to S. 

 patzcuarensis, but differs by its much larger size, concave 

 columella and tapering spire. 



