SOUTH AMERICAN OPEAS. 209 



Ecuador: Guayaquil (type loc., Dr. Th. Wolf) ; Guatemala 

 and Eastern Mexico (Strebel). 



Opeas rarum MILL., Malak. Bl. (n. F.), i, p. 125, pi. 14, f. 2 

 (1879). STREBEL, Beitrag Mex. etc., v, 1882, p. 103, pi. 17, 

 f. 8, 17; pi. 7, f. 5. 



Differs from 0. acutius Mill. [0. subula Pfr.] by the wider 

 shape, more convex whorls, narrower perforation, greater 

 gloss, reddish color of the upper whorls, and the more strongly 

 retracted base of the aperture. The very delicate growth- 

 strias are strongly arcuate. (Mill.) . 



Strebel remarks that Miller's type which he examined has 

 not such terraced whorls as 0. octonoides, and the last whorl 

 is represented too full in Miller's figure (copied on my 

 plate). The larger of Miller's two specimens measures 8.4 

 mm., with 6y 2 whorls. The whorls may increase in height and 

 breadth a little faster than in octonoides. The shell is glossy, 

 and has a sculpture more like 0. subula than like octonoides 

 or lucidum, the columellar reflection also resembling that of 

 siibula more than that of caraccasense [beckianum] or even 

 octonoides [micro,] . The same form according to Strebel was 

 collected by Stark at San Miguel Jucuma, Guatemala. A 

 form referred by Strebel to the same species as a "form B" 

 was taken by him at the plantation Mirador (State of Vera 

 Cruz) . It is somewhat smaller, 7.2 mm. long with 6% whorls, 

 the whorls are more distinctly terraced, and the sculpture is 

 a little more sharply developed than in typical 0. rarum. 



It is not known to me by specimens. 



13. 0. CAMBA (Orbigny). PI. 27, figs. 50. 



Shell much elongated, turriculate, thin, little transparent, 

 smooth to the naked eye, but seen to be perceptibly striate un- 

 der the lens ; spire elongated, nearly conic, with obtuse apex ; 

 composed of 9 swollen whorls, quite wide and separated by a 

 deep suture. Aperture oval, straight, with acute peristome, 

 visibly reflexed, the columella flattened and recurved, leaving 

 a sort of umbilicus. The general tint is dull white or a little 

 brownish, the lip white with an indication of a light violet 

 border. Alt. 14, diam. 4 mill. (Orb.) . 



