140 



transverse ridges cross the spiral ridges with enlargement- 

 We propose for it the name of docens, in allusion to its in- 

 structiveness on the question of the origin of varieties. 



A specimen of Cyclostoma iincina from the mountains 

 behind Spanish Town is remarkable for its size and the devel- 

 opment of the outer peritreme. Its dimensions are — mean 

 divergence 54° ; length 1 inch ; greatest breadth .77 inch ; 

 least breadth .6 inch : transverse diameter of the aperture .3 

 inch, and including the peritreme .57 inch I 



On pages 91 and 93 of Contr. Conch, two varietie sof one 

 species were accidentally published as distinct species, with 

 the names of C. nodulosum and C. granosum. These varie- 

 ties differ slightly. The name, 0. granosum, having appeared 

 in Mr. Redfield's catalogue, and being rather more appropriate, 

 may be adopted to the exclusion of the other. Another vari- 

 ety of this species occurs, in which the last whorl is much 

 detached from the penult whorl. It is also entirely destitute 

 of the purplish brown color anteriorly. The two individuals, 

 which we have received on loan from Mr. Chitty, make us 

 acquainted with the operculum of this species. It has a spi- 

 ral lamella, well elevated, of more than three whorls. The 

 variety may be designated by the name of aberrans. 



Analysis of the Gh'oup of Species of Cyclostoma, ichich is 

 represented by C. Jamaicense Chem. 



This group has been more or less known for nearly sixty 

 years under the name proposed by Chemnitz. In March, 

 1843, Mr. Sowerby, (Proc. Zool. Soc. Lond. and Thes. Conch. 

 I. p. 95, pi. 23, f. 10, 11,) described a second species under the 

 name of C corrugatwn. Both species have been repeated 

 by Dr. Pfeiffer in Kuster's Cyclostomacea. During the pres-> 



