352 DR. p. p. CARPENTER ON THE SHELLS OF PANAMA. [June 23, 



Ch. C-B-Adamsii, M. 519, with straight ribs; and one with spiral 

 sculpture, which may belong to Oh. gracillima, M. 530, but wants 

 the produced apex. 



228. Chemnitzia similis. This species most nearly resembles 

 aculeus, but is broader, larger, and with more ribs, of which I counted 

 from twenty to twenty-two (not twenty-six). I should not call the 

 whorls " convex." They are, however, more rounded, and the base 

 is more produced, than in the shell called " 1 similis," M. 520, which 

 is perhaps a variety o{ panatnensis. 



229. Chemnitda striosa. The early whorls are very slender. 

 The spiral striae are on the tops of the ribs, of which I counted from 

 twenty-four to thirty-two (instead of "about forty"). 



230. Chemnitzia turrita. This species includes the "Rissoa, 

 sp. ind." no. 251. 



23 1 . ? Littorina angiostoma is a Fossarus. 



232. Littorina aspera, M. 39". The Mazatlan periwinkles, being 

 in good condition, divide themselves very naturally into three 

 species. The Panama specimens, being generally eroded, are not so 

 easily dealt with. Of Prof. Adams's specimens here retained, the 

 majority belong to aspera, although several of the smaller ones are 

 philippii, M. 398. The young appear to be of both species mixed. 

 The " variety " consists of the abnormal tall specimens of conspersa, 

 M. 396, with a few very large philipjiii intermixed. 



233. Littorina atrata. This abundant little shell is a Fossarus, 

 of which the Professor's lAdeorbis abjecta, no. 257, is a more ad- 

 vanced form. It is possible that one of the Fossari described in 

 Maz. Cat., nos. 404, 405, may be conspecific ; but among the mul- 

 titude of specimens I could not find one with the nuclear whorls 

 sufficiently perfect to decide. The shells vary extremely in shape 

 and sculpture. 



234. Littorina conspersa, M. 396. Smaller and generally more 

 stumpy than the Mazatlan shells, but containing a few specimens of 

 the same extreme forms. 



235. ? Littorina exeavata^ Fossarus e. 



236. Littoiina fasciata, M. 400. The specimens of this species 

 and of L. varia graduate rather closely towards each other. 



237. ? Littorina foveata. A good species of Fossarus. Read, 

 " Last whorl angular" at the umbilicus [not " below the middle"]. 



238. 1 Littorina megasoma. This is also a good species of FoS' 

 sarus. The Professor was doubtful whether to refer these forms to 

 Littorina or to Narica. 



239. Littorina 1 parvula, C. B. Ad. This is not Phihppi's L. 

 parvula, but is a dwarf form of the L. philippii, M. 398. The Pro- 

 fessor suggests the name L. dubiosa for this sufficiently well-marked 

 species ; but as he catalogued and distributed his specimens under 

 1 parvula, and kept others under aspera, it may be best to retain 



