370 , LITTORINID^E. 



more circular than in the last species, but, though paucispiral, 

 the turns are less distinct, the oblique strise of increment 

 coarser, and the colour instead of being clear white is a dull 

 yellow. All this is different in the 'proximo,.' 



The examples now described are the only two that have 

 occurred of this rare animal ; it and the ' proximo, ' were 

 placed in the same glass, and, being lively, I had good oppor- 

 tunities for comparison ; the animals are organically different, 

 but I think the 'proximo, 3 is a greater departure from the 

 Bissoidean type than the 'vitrea'', still it will probably re- 

 main with the Rissoce, though some of the specialties are on 

 the verge of generic deviation. 



In the remarks on these species I fear that conciseness is 

 neglected, but the confusion, in which they have long been 

 enveloped must be the apology, as, without the present close 

 examination, the doubts of their identity or distinctness 

 would still have remained, and the slight, though constant, 

 difference of contour in the two would by many be considered 

 accidental. 



It may be useful to the shell collector, to the younger 

 student, and as a memorandum of the remaining desiderata 

 of this genus, to offer a few short remarks on all the British 

 Rissoae not enumerated above. 



The animal of the elaborately sculptured R. striatula, the 

 most elegant of the Rissoce, if it be one, still escapes observa- 

 tion. I have taken some delicate specimens in the coralline 

 district, and yet hope to see the inhabitant. 



The R. lactea of Michaud I do not know, but from the 

 figure in ( Brit. Moll/ I should have judged it a variety of the 

 R. reticulata, one of the large, short, tumid shells, and would 

 have said the same of the R. abyssicola, if it had not been 

 considered distinct by Professor Forbes. The R. crenulata is 

 the well-known Turbo cimex, as the R. calathus is the old 

 1 calathiscus ' of authors : neither of the animals are recorded. 

 The R. Zetlandica is a well-established northern species, but 

 the inhabitant is unknown. 



