VARICELLA, JAMAICA. 79 



reflected in the lower half: columella moderately produced, 

 nearly straight., well truncated. Mean divergence about 20 ; 

 length of spire .65 inch; total length .86 inch; 'breadth .27 

 inch." (Adams.) 



Jamaica: Pedro, St. Ann's (J. S. Hyde, in Adams coll.). 



Achatina costulosa C. B. A., Contrib. to Conch, no. 6, p. 

 102 (March, 1850). 



Typical specimens, agreeing exactly with Adams ' types, are 

 figured on plate 7. The first 1% whorls are smooth. Then 

 rib-striae of the adult type abruptly appear. Sometimes the 

 first two or three riblets after the smooth apex, do not ex- 

 tend to the suture below. The riblets are as wide as the 

 intervals, nearly five in a mm. on the last whorl. The later 

 whorls have about three inconspicuous varices, which are not 

 preceded by brown streaks, at least in the "deiad" specimens 

 an collections I have seen. The outer lip is nearly in a plane, 

 but weakly arched forward. The columella is very short, 

 curving into the parietal wall above, obliquely truncate at 

 base. Length 22, diam. 6, aperture 6.4 mm., whorls 8 l /2- 



V. costulosa seems to be rare. I have never seen a fresh 

 adult shell. There is a fresh young one in the Adams col- 

 lection, of a clear corneous tint, translucent at the smooth 

 base and apex. 



This species is not closely related to the preceding, yet it 

 seems nearer to them than to the typical section of Varicella. 



Section VARICELLARIA Pilsbry, n. sect. 



First i/o to li/o whorls smooth; neanic and mature stages 

 regularly ribbed or rib-striate, the intervals as wide as the 

 stride ; columella distinctly truncate at base. Type V. procera. 



All of the species are from Jamaica. 



The forms which are ribbed almost to the apex seem quite 

 distinct from typical Varicella as the acute Strebel has al- 

 ready noticed; yet all stages in the acceleration of rib-sculp- 

 ture are to be found in the several species, so that the taxo- 

 nomic value of the character in this case is not great. 



Key to species. 

 I. First i/o to % of a whorl smooth, the rest ribbed. 



