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



the name philippii under which it has been very extensivelv ctr»*-- 

 lated. 



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

 fasciata and varia) to the Meluraphe group. 



241. Littorina puncticulatu. This Is the normal state of L. con* 

 tpena : v. M. 39f). 



242. Littorina varia : v. note on P. 2.36. 



24.'?. Rissoa clandestina. Three specimens appear of this spetit? 

 o{ Rissnina, closely resembling R. wootfwirdii, M. 410, but with 

 more ribs, and not displaying the intercostal striulse. 



244. Rissoa finnata. Another species of Rissoina, resembling 

 R. strict (I, M. 408, but smaller. Tiie Professor did not observe 

 the fine spiral sculj)ture, as described in no. 2.")0 ; q. v. 



24.5. Rissoa fort is. A good species of Rissoina, differing from 

 R.jamts in the absence of spiral punctures. 



240. 1 Rissoa inconspicua, C. B. Ad., nou Alder. The name 

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

 tical with Alcania 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 infrequena. 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 drawTi 

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

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

 as the tyj)e, 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 notahilis. After drawing this \uiique 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 

 caa state with perfect confidence that it was exactly identical with 

 another siiell iu t\\e collection, P. 2aJ, q. v. ; and with M. 498, 

 Parthenia quinquecincta. The " concave summits " of the ril)s 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 bioken, the columellar plait, as well as the sinistral apex, 

 esr,aped the Professor's notice. 



250. Rifisoa scalariformis. This unique specimen is simply the 

 young of Rissoina Jirmata, P. 244; and probably =; Rissoina sp. 

 ind. M. 409. ^gg 



