1899.] NATURAL SCIENCES OF PHILADELPHIA. 399 



Whorls 7^, very convex, separated by deeply impressed sutures ; 

 first half whorl smooth, following whorl very finely lamellose- 

 striate; succeeding whorls with numerous, delicate, raised riblets, 

 about 42 in number on the penultimate whorl. Aperture short- 

 oval, somewhat trapezoidal; columella thick, strongly sinuous. 



Alt. 5.2, diam. 2 mm. 



Uruapam, State of Michoacan, Mexico. 



This species is more obtuse than *S'. svlciferus and its variety 

 herendti; has more convex whorls than S. tenuecostatus Strel). , and 

 is stouter than *S'. miradorensis Streb., with closer riblets. S. 

 tenuis is an allied form, which should be compared. 

 Opeas patzcuarense u- f=p. 



Shell minute, slender, obtuse at tlie apex, slowly tapering, 

 rather cylindric or rod-shaped. Whitish corneous, glossy and 

 smooth, showing slight, sparse growth wrinkles under a lens. 

 AVhorls 7^, moderately convex, the last tapering at base. Aper- 

 ture long, irregularly ovate; columella straight, vertical. 



Alt. 3, diam. 0.8 ram. 



Patzcuaro, State of Michoacan, Mexico. 



A very small species, unlike any other Mexican form known to 

 me. Numerous specimens were collected. 

 Opeas odiosum n. sp. 



Shell slender, turreted, completely imperforate, corneous, suffi- 

 ciently translucent to show the columella faintly through. Surface 

 glossy, irregularly scored by unequally spaced longitudinal grooves 

 and some slight wrinkles. General outlines of the spire straight; 

 apex obtuse. Whorls 8^^, the earlier strongly convex, the last two 

 slightly flattened. Aperture ovate; outer lip thin, moderately 

 arched forward, columella slightly concave, forming a distinct 

 angle with the parietal wall. Alt. 6.9, diam. 2, longest axis of 

 aperture 1.5 mm. 



Patzcuaro, State of Michoacan, Mexico. 



The impressed grooves are similar in character to those of Vitrea 

 indentata and other species of Glyphyalinia. About forty speci- 

 mens were collected. 

 Opeas rhoadsae n. sp. 



Shell slender, subulate, wholly imperforate, corneous and suffi- 

 ciently translucent to show the internal axis through the shell in 



