SPIRAXIS. 15 



Urocoptida. The embryonic shell resembles that of Picfc 

 ardiella. 



1. S. INUSITATUS (. B. Adams) . PI. 1, figs. 1, 2. 



"Shell elongated, gradually tapering in the upper half, 

 cylindrical in the lower half, wide and blunt anteriorly, with 

 a broad very deep constriction about the middle of the last 

 whorl ; dingy white ; with very distinct lamellif orm transverse 

 ribs, about ten on< each whorl, with strong irregular interve- 

 ning striae ; spire with convex outlines ; apex small ; whorls nine, 

 very convex, with a deeply impressed, and near the apex a 

 chanelled, suture; last whorl small and very short; aperture 

 ovate, acute above, much modified by the constriction of the 

 last whorl, which constriction bends the sharp labrum into 

 two large arcs of small circles ; columella remarkably twisted 

 and arcuate. Length .16 inch; breadth .05 inch; length of 

 aperture .033 inch/' (Adams.) 



Jamaica : 



Achatina inusitata C. B. AD., Contrib. to 'Conch, no. 2, p. 

 26 (Oct. 1849). Spiraxis i, AD., Contrib. no. 6, p. 88. PPR., 

 Monogr. iii, 471. 



This species is related to S. mirabilis, but the whorls are less 

 swollen, the -ribs not so prominent and the columella is dis- 

 tinctly truncate at its base. It is dull buff- white, with about 

 five ribbed whorls, those above being finely and delicately 

 costulate and more drawn out. The first whorl seems to be 

 smooth. The spire is suddenly attenuated above the ribbed 

 whorls, as in S. mirabilis. Within the last whorl or more 

 the>re is a peripheral row of small denticles, usually visible 

 through the shell as pale or opaque spots. Length 4, diam. 

 1.1 mm., with 9 whorls. 



The columellar lamella enters somewhat more than one 

 whorl, but the axis is simple and straight in the second whorl 

 from the base as well as in all preceding ones. Below the 

 main lamella of the axis there is a second much smaller one, 

 terminating at the base of the columella which appears obli- 

 quely truncate. In the last whorl there is a strong parietal 

 lamella, which does not extend to the aperture (fig. 2). 



