418 



FUNAFUTI ATOLL. 



RlSSOA INVISIBILIS, sp. DOV. 

 (Fig. 



Shell small, sturdy, 

 conic ovate. Colour 

 white. Whorls four. 

 Sculpture distant, 

 longitudinal, sharp 

 costse are crossed by 

 three similar spiral 

 ribs, which together 

 divide the surface 

 into nearly square 

 compartments ; at 

 the intersections are 

 small projections. 

 One spiral ridge 

 alone appears on the 

 Fig- 9. penultimate whorl, 



both it and the longitudinals vanish on the whorl above. The 

 base is flattened, umbilicus narrow and deep. Aperture round, 

 columella slightly sinuate, recurved over the umbilicus, lip with 

 a heavy varix. Length 1'15, breadth '63 mm. 

 One specimen from the sand of the lagoon shore. 

 Shape and sculpture ally this to the group including R. trajectus, 

 Watson. The heavy lip, open pattern of ornament, and com- 

 parative breadth of the shell clearly distinguish the novelty, one 

 of the smallest of the genus, from any known form. 



RISSOINA EXASPERATA, Souverbie. 



(Pig. 10). 

 Souverbie, Journ. de Conch., xiv., 1866, p. 259, pi. 



ix., fig. 10. 



To this species is referred with doubt a series from 

 Funafuti. The published account is insufficient for 

 accurate determination, and my principal reason for 

 considering the Ellice shell to be R. exasperata is its 

 identity with a common New Caledonian shell 

 which I have myself collected at Panie, N.C., and 

 have received from Noumea, from Mr. R. 0. 

 Rossiter, That Conchologist regards it as R. ex- 

 asperata, and it answers fairly to Souverbie's 

 description as far as that goes, but it is less easy to reconcile it 

 with his figure. 



This figure, perhaps drawn from a worn specimen, was so badly 

 copied by Weinkauff* as to almost eliminate the name character 

 and represents a smooth exasperata. Tryou unfortunately appears 



Pig. 10. 



Conchylien Cabinet, i., 22, 1885, p. 54, pi. xiv., fig. 10. 



