VOLUTAXIS. 51 



P. TROCHLEA, PfeifFer. PL 9, fig. 34. 



Thin diaphanous, shining, 3'ellowish white, obliquely minutely 



striate ; whorls 10, suture profound. Length, 23 mill. 



Mexico. 



Genus VOLUTAXIS, Strebel and Pfeffer, 1882. 



Y. SULCIFERUS, Morelet. PL 9, fig. 38. 



Subdiaphanous, elegantly longitudinally costulate, light cor- 

 neous , whorls 8, convex ; columella white. Length, 8 mill. 



Guatemala. 

 Y. BERENDTII, Pfeiffer. PL 9, fig. 30. 



Rather thin, subhyaline, closely plicate, whorls 8. 



Length, 7 mill. 



Mirador, near Vera Cruz, Mexico. 



Perhaps only a variety of the preceding species. V. euptyctus, 

 Pfr. (unfigured), is considered a synonym by Strebel. 



Y. TENUECOSTATUS, Strebel. PL 9, fig. 39. 



Distinguished from the two preceding species by its more 

 obtuse apex, fewer whorls and finer ribs.' 



Mexico. 

 Described from a single specimen. 



Y. SIMILARIS, Strebel. PL 9, fig. 40. 



Differs from V. sulciferus principally in its narrower, more 



cylindrical form. 



Near Jalapa, Mexico. 



V. Miradorensis, Strebel, is possibly an abnormal or local form 

 of V. similaris, as suspected by that author. 



Y. CONFERTECOSTATUS, Strebel. PL 9, figs. 41, 42. 



Distinguished from the last species by its more slender form, 

 more acuminated spire, higher whorls, and especially by its 

 much finer and more numerous ribs, 55 to 60 in number. 



Xear Jalapa, Mexico. 



Y. iNTERMEDius, Strebel. PL 9, figs. 43, 44. 



Resembling the preceding species, but stouter, with about 40 

 ribs somewhat impinging on the sutural line. 



Near Jalapa, Mexico. 



