40 C^CILIOIDES OF TROPICAL AMERICA. 



erroneously lettered A michaudiana on plate (1845); French 

 edit, i, p. 170. Achatina pygmaa PFR. , Zeitschr. f. Malak. 1847, 

 p. 148; Monogr. ii, 275; iii, 506; iv, 627; vi, 241; Conchyl. 

 Cab. p. 356, pi. 29, f. 22, 23. Cacilianella pygmaa Pfr. ARANQO, 

 Fauna Malac. Cubana, p. 99. 



This species is closely related to C. iota, from which it differs 

 by the stouter, more robust figure, specimens of the same length 

 being invariably wider than iota. The general shape is slightly 

 tapering cylindric, very obtuse at the ends. The whorls in- 

 crease a little more regularly than in iota, the last turn of the 

 suture being less oblique, though descending faster than the 

 preceding one. This acceleration of the rate of descent changes 

 the appearance of the shell and the proportionate size of aperture 

 to total length with age, so that the addition of a whorl or even 

 less alters the contour remarkably. The surface is lightly 

 marked with growth-wrinkles and minute engraved spiral lines, 

 visible only under a compound microscope. The columellar 

 truncation is distinct, but rather weak in some examples. Two 

 specimens from a lot taken by Gundlach are figured. 



PI. 5, fig. 82: length 2.4, diam. 0.8 mm. 



PI. 5, fig. 81: length 1.9, diam. 0.7 mm. 



The former of these examples corresponds to the type of 

 A. pygmaa Pfr. ; the latter, a younger shell, agrees with Orbigny's 

 type of A. consobrina. In my opinion these two names apply 

 to one and the same species, in slightly different stages of 

 growth. Pfeiffer's description of A. pygmaa follows. 



" A. pygmaaPh. Shell cylindric, smooth, pellucid hyaline, 

 the apex rather obtuse. Whorls 5, rather flattened, separated 

 by an oblique, lightly impressed suture, the last f the total 

 length. Columella nearly straight, forming an angle with the 

 belly of the preceding whorl, subtruncate at the base of the 

 oval-elliptical aperture; peristome acute, the right margin 

 dilated forward. Length 2.25, diam. f mm.; aperture f mm. 

 long." (Pfr.) 



Var. veracruzenm (Crosse & Fisher). PI. 5, figs. 76, 77, 78, 

 79. In this form the microscopic spiral striation is more dis- 

 tinctly developed than in consobrina, visible from the suture to 

 the base, the striae appearing crimped or waved (fig. 79). 

 There is no other difference. Specimens measure: 



