3/8 MR. R. B. WATSON ON MADEIRAN M0I..LUSKS. [Mar. 18, 



Hab. Grorgulho, shore ; Santa Cruz, shore to 15 fathoms; Ma- 

 chico, 10-15 fathoms; Piedade (Canigal), 15-35 fathoms; Ponta 

 de S. Louren<jo, 25-45 fathoms; Funchal Bay, up to 50 fathoms; 

 Porto da Cruz, up to 50 fathoms. 



From R. canariensis this species differs in its squat and conical 

 form, in not rising at all in steps, in having more numerous 

 and flexuous ribs, more numerous and less-marked spiral threads, 

 and the tendency of these to disappear instead of to become mucronate 

 on the crests of the ribs. 



From jR. punctura it differs in that it is much squatter, much 

 more strongly sculptured, much more brilliant in colour, has fewer 

 whorls, and terminates much more abruptly in a flattened and 

 stained apex. The embryonic whorls are I5 (not 2^) to 3 ; and their 

 spiral lines are formed of approximate stipplings, not, as in R. 

 punctura, of remote .tubercles. 



The name was suggested by Baron Schwartz v. Mohrenstern, to 

 whom I had sent the species for description. He wished in this way 

 to recall the frigate 'Novara,' employed by the Austrian government 

 on a scientific voyage round the world. The name is unfortunately 

 not very appropriate, but is better than a new name, whose substi- 

 tution might breed confusion, an already sadly prevalent misery in 

 scientific nomenclature. 



The species is accepted as unquestionably new by Baron Schwartz 

 and by Mr. Gwyn Jeffreys. 



Piissoa violacea, Desmarest. (Plate XXXV. fig. 14.) 



In M'Andrew's list. 

 Hab. Porto Santo, up to 50 fathoms. 

 A subarctic, European, Mediterranean, and Canary species. 

 Mr. M' Andrew, in his 'List of Atlantic Mollusca,' has, through a 

 slip of the pen, given this as R. purpurea. 



Rissoa costulata, Alder. (Plate XXXV. fig. 15.) 



Not in M'Andrew's Madeiran list. 



Hab. Piedade (Cauical), 25-35 fathoms ; Ponta de Sao Lourenc.o, 

 25-45 fathoms ; Funchal Bay, up to 50 fathoms ; Porto da Cruz, 

 up to 50 fathoms. 



A European and Mediterranean species. 



In accordance with the present received opinion I accept R. 

 violacea and R. costulata as distinct species. Beyond question they 

 can be distinguished : R. costulata is on the whole more drawn out 

 altogether aud in all its parts than the other ; but the best mark of 

 distinction is that it has the spiral strife stippled with minute, equal, 

 close-set, longitudinally elongated dots ; while in R. violacea these 

 pitted dots are much larger, are variable in size, are parted by broad 

 Hat bars, and are elongated across, i. e. in the breadth of the shell. 



The whole of these differences, however, really resolve themselves 



