124 Miscellaneous. 



Variations in Bulimus exilis. 



Dr. Benjamin Sharp called attention to two varieties of Bulimus 

 exilis which he had found on the islands of Guadeloupe and Dominica. 

 One variety was characterized by broad dark brown bauds which 

 run ])arallel with the coil of the shell, while the other was peculiar 

 in possessing small and very faint bands, which in many speci- 

 mens were entirely absent. The banded variety was found to be 

 common in Guadeloupe, while the bandless one was rare. In 

 Dominica, which is separated from Guadeloupe by a channel of only 

 twenty-three miles, the banded variety was very rare, while the 

 light or bandless one was comparatively common, although indi- 

 viduals were by no means so common in Dominica as in Guadeloupe. 

 He spoke of the probable cause of the variation, and suggested that 

 it was due to some environmental action. The island of Dominica 

 being wholly of volcanic origin would produce a different kind of 

 food from the Grande Terre portion of Guadeloupe, which in forma- 

 tion is purely coral. It was on this portion of Guadeloupe that the 

 specimens of B. exilis were collected. It is known that Dominica 

 has many species and some genera of plants that are peculiar to the 

 island, and this difference of food may in some way account for the 

 differences in this species of land-snail. Dr. Sharp said that it is 

 probable that the dearth of land-shells on the volcanic islands and 

 their comparative plenty on the coral and continental islands of the 

 Caribbean group is due to the absence of carbonate of lime in the 

 former and its presence in the latter. 



HemarJcs on the Exuvice of Snalces. 



Dr. Benjamin Sharp further spoke on the exuvite of two snakes, 

 which were shed in the laboratory of the Academy two days pre- 

 viously. These snakes, Eiitanceia sirtalis, B. & G., had been pre- 

 sented to the Academy on the 19th of March, 1890, and had been 

 captured the day before in New Jersey. The whole process of 

 shedding the skin had been observed. One of the snakes was in the 

 water when first seen, and, coming out upon the sod, it shrugged 

 and shook itself for a moment ; then, getting between the glass of 

 the vivarium and the box containing the earth, the skin parted at 

 the jaws and the animal crawled out, leaving the exuvia. The 

 cerebral portion being fixed, the animal passed through the opening, 

 so that the discarded skin, as is always the case, was turned wrong 

 side out. One of the specimens was interesting as it was entirely 

 perfect, without the slightest rent and not a scale missing. The 

 other was perfect, but there was a considerable rent on each side of 

 the jaw. The operation took less than one minute. The snake was 

 startled about the middle of the process. It crawled away from the 

 exuvia very rapidly. — Proc. Acad. Nat. Sci. Fhilad., April 15, 1890, 

 pp. 148 and 149. 



