422 FUNAFUTI ATOLL. 



development of the basal rib, and the number of longitudinal 

 plications vary also. The transverse markings are not grooves, 

 as Adams' description would mislead one to suppose, but elevated 

 threads. The difficulty I found in naming this species induces me 

 to offer a drawing for the assistance of others. 



Authentic specimens of R. turricula, Pease, from Hawaii, en- 

 able me to unite it with the above, a conclusion which Weinkauff's 

 bad figures would not have suggested. 



A specimen from British New Guinea is contained in this 

 Museum. Tryon quotes jR. turricula from Fiji. 



RlSSOINA AMBIGUA, Gould. 



Gould, Moll., U.S. Explor, Exped., p. 217, pi. xv., figs. 261a-c; 

 Tryon, Man. Conch., ix., 1887, p. 371, pi. lv., figs. 27, 29, 31, 

 35 ; pi. liv., fig. 7. 



A few worn specimens were collected on the lagoon beach. 

 They belong to a variety with smaller and more numerous ribs 

 on the last whorl than the type. 



This is one of the most abundant and widespread species in the 

 Pacific. It was first found in the Paumotus Group. I have 

 seen specimens from Tahiti. Pease found it in the Hawaiian and 

 Garrett in the Fijian Islands. I have collected it in Port Moresby, 

 New Guinea, and again at Panic, New Caledonia. 



RISSOINA AFFINIS, Garrett. 

 Garrett, Proc. Acad. Nat. Sci. Phil., 1873, p. 212, pi. ii., 



fig. 10. 



One specimen from the lagoon beach resembles Garrett's figure 

 and description, but differs in being microscopically striated above 

 and below the periphery, and also in being eight instead of 5 mm. 

 long. 



RISSOINA SPIHATA, var. SUPBACOSTATA, Garrett. 

 Garrett, loc. cit., p. 209, pi. ii., fig. 1 ; Tryon, LOG. cit., p. 388. 



A small specimen, even more drawn out than Garrett's figure, 

 from the lagoon beach. 



DlALA VIBGATA, Sp. nov. 



(Fig. 14). 



Shell imperforate, narrow, regularly conical, obtusely angled at 

 the periphery, blunt at the tip, surface dull. Colour most variable, 

 typically about half-a-dozen broad, irregular, opaque, white stripes 

 extend longitudinally upon a translucent white ground from the 

 suture to beyond the periphery of the last whorl, and cross the 

 full breadth of the earlier ones. The translucent ground, but not 

 the opaque patches, are crossed by an indefinite number, commonly 



