UR. P. P. CARPENTER ON THE SHELLS OF PANAMA. 15 



the name philippii under which it has been very extensively col- 

 lated. 



240. Littorina pulchra. A very rare species, belonging (witfc 

 fasciata and variety to the Melaraphe group. 



241. Littorina puncticulata. This is the normal state of L. co- 

 gpersa : v. M. 396. 



242. Littorina varia : v. note on P. 236. 



243. Rissoa clandestina. Three specimens appear of this specks 

 of Rissoina, closely resembling R. woodwardii, M. 410, but with 

 more ribs, and not displaying the intercostal striulse. 



244. Rissoa firmata. Another species of Rissoina , resembling 

 jR. stricta, M. 408, but smaller. The Professor did not observe 

 the fine spiral sculpture, as described in no. 250 ; q. v. 



245. Rissoa fortis. A good species of Rissoina, differing from 

 R. janus in the absence of spiral punctures. 



246i ? Rissoa inconspicua, C. B. Ad., non Alder. The name 

 being preoccupied, it is fortunate that the unique shell proves iden- 

 tical with Alvania tumida, M. 414. I found twenty (not "twelve 

 or fourteen ") ridges, which are not " obsolete," but become fainter 

 anteriorly. The two upper whorls are very finely cancellated. 



247. Rissoa infrequens. The unique specimen of this Rissoina 

 is too much worn for description. It has more than the sixteen ribs ; 

 and the diagnostic marks must be received with caution. 



248. Rissoa janus. The description of this Rissoina is drawn 

 from a very small, dead, broken specimen, from which the sculpture 

 is almost entirely worn away. The " var. a " should be considered 

 as the type, being in perfect condition, and the diagnosis be altered 

 as follows : The "fine crowded spiral striae" are seen all over, as 

 are also the "ribs," which on each whorl "appear as striae," and 

 are not " obsolete near the periphery." The diagnostic character is 

 that the spiral striae are composed of rows of minute dots. 



249. Rissoa notabilis. After drawing this unique shell carefully 

 under the microscope, and making copious notes on the diagnosis 

 from the specimen, an untoward cough lodged it among the meshes 

 of the Curator's carpet, whence I endeavoured in vain to extricate it. 

 This unfortunate accident is, however, the less to be regretted, as I 

 can state with perfect confidence that it was exactly identical with 

 another shell in the collection, P. 255, q. v. ; and with M. 498, 

 Parthenia quinquecincta. The " concave summits" of the ribs imply 

 that the ribs are sharp, with concave interstices ; and the " upper 

 keel " is simply due to the angulation of the whorls. Though the 

 lip was broken, the columellar plait, as well as the sinistral apex, 

 escaped the Professor's notice. 



250. Rissoa scalariformis. This unique specimen is simply the 

 youn<r of Rissoina firmata, P. 244: and probably = Rissoina sp. 

 ind. M. 409. 



