RISELLA. 263 



views. I retain Gmelin's name for the species, although it cannot 

 be satisfactorily identified, because it is the oldest name, and by 

 common consent for many years has been generally applied to one 

 or another of the above forms. 



Subgenus PEASIELLA, Nevill., 1884. 



R. TANTILLA, Gould. PL 50, figs. 32, 33, 34. 



Perforate, whorls 4-5, flattened, with carinate periphery, ob- 

 liquely very finely striate, base with two spiral granular threads ; 

 yellowish ash, sometimes showing radiating, flexuous chestnut lines, 

 aperture orange-brown. Diam. 4-5 mill. 



Sandwich Is., Viti Is., Australia, Ins. Nossi-be. 



It is Margarita angulata, A. Ad., Trochus diminutivus, Reeve (fig. 

 34), R. parvula, Dunker, var. subinfraeostata, Nevill. 



R. CALEDONICA, Grosse. PL 52, fig. 9. 



With wide funnel-shaped umbilicus defined by a carina, another 

 carina on the periphery, a third at the suture, microscopically stri- 

 ate longitudinally, yellowish brown ; whorls 4, angulated by the 

 carinse, rapidly increasing, base flatly convex. Diam. 2'25 mill. 



New Caledonia. 



Described as a Fossarus. It appears to differ from the other 

 species by its wider umbilicus. 



R. GAIDEI, Montr. PL 50, figs. 35-37. 



Umbilicated, spirally striated, periphery acutely carinated and 

 denticulate by the projection of longitudinal, rounded ribs ; yellow- 

 ish white, spirally articulated with brown above the periphery and 

 on the base. Diam. 2*75 mill. 



Li/ou, Loyalty Is. 

 R. CONOIDALLS, Pease. PL 50, fig. 38. 



Narrowly perforate ; whorls flatly sloping, spirally grooved, pli- 

 cately longitudinally wrinkled, undulating the carinal line, base 

 flatly convex, finely grooved ; whitish, stained with saffron yellow. 



Diam. 4 mill. 



Paumotus. 

 R, ISSKLI, Semper. PL 50, figs. 39, 40. 



Umbilicated, spirally engraved above, costate on the base, upper 

 part with low, broad, rounded undulations or ribs, modifying the 

 carinated periphery ; yellowish, articulated with brown at the 

 suture and periphery. Diam. 2*5 mill. 



Suez, Zanzibar. 



