1870.] On the Zand Shells of Bourbon. 403 



I have named tins shell after M. Jacob de Cordenioy, 

 a well known botanist at Bourbon. 



18. Stenogyra (Opeas) clayulinus, Pot. and Mich. Gall, de 

 Douai, I, p. 136. 



This little Bourbon Opeas is easily distinguished at a glance from 

 the still more common and widely spread group, (0. gracilis, 

 Hutt., O. Mauritiana, Pfr. &c.,) by its more polished and shining 

 appearance, by its being devoid of regular and distinct striation, by 

 its more swollen and more rapidly increasing whorls, this difference 

 being especially noticeable in the first few whorls near the apex, by 

 its more angular aperture, &c. ; it is, I believe, the shell described 

 by Pfr. Mon. Hel. Yol. I. p. 159, in the foot note marked with 

 a single asterisk, where it is referred to the Bui. clavulinus of P. and 

 M., he there gives the length of the species as 8 mill., this is probably 

 my var. A. ; in Vol. III. he re-describes the species from a Mauritian 

 specimen, where he gives the length as only 6 mil. &c, agreeing with 

 my var. B. I have never seen this species from Ceylon or any part 

 of India, though the other group of 0. gracilis &c, is as abundant 

 at both, as at Mauritius and the Seychelles ; I did not, however, find 

 my var. B. of 0. clavulinus at Bourbon, though I expect both it and 

 Opeas Mauritiana and gracilis will eventually be discovered there ; 

 the habits of the subgenus Opeas are more favourable, than perhaps 

 those of any other mollusk, to their introduction into distant coun- 

 tries, they are to be found in cultivated spots nearly everywhere, 

 even in the gardens of large cities like Calcutta and Port Louis, where 

 they bury themselves in the ground amongst the roots of plants, &c, 

 sometimes under stones. 



I divide this species (0. clavulinus, P. and M.) into two forms or 

 varieties — 



A. Whorls seven, the last one especially not quite so tumid as 

 in the next variety. Bourbon, Mauritius and the Seychelles. 



Long. 8£, diam. maj. 3 ; long, apert. 2f, diam. !■£ m. m. 



B. (Pfr. Mon. Hel. III. p. 394). Whorls six, broader in pro- 

 portion to their length than those of the preceding. Mauritius and 

 the Seychelles. 



Long. 6, diam. 2f ; long, apert. 2 J, diam. 1£ m. m. 



