THE MOLLUSCA HEDLEY. 



445 



feebly divided from one another, that they seem rather to be a 

 continuous keel, like that of T. corrugatus, in process of breaking 

 down into beads. The earlier adult whorls are ornamented by 

 two bead-rows. Between them there arises in the antipenultimate 

 a thread, which gradually increasing becomes a full grown row in 

 the last whorl ; the addition of a median and two basal rows brings 

 the number of rows on the last whorl to six. Tryon states that 

 the " three anterior ones are unarmed," but all are beaded in the 

 example before me. 



Fig. 31. 



The anal notch is simple and comparatively shallow. The 

 protoconch has five whorls, the first hemispherical and smooth, 

 the others bicarinate and obliquely crossed by rather coarse bars 

 which do not bead the carinae. The adult sculpture suddenly 

 commences in the sixth whorl with a row of small beads above 

 and a large gemmed ridge below. The latter is remarkable in 

 several specimens before me for its white colour, giving the shell to 

 the unaided vision a distinct white collar beneath the acicular 

 apex. Tryon gives the length as 8 mm. Of the examples before 

 me the New Caledonian measure 4, the Papuan 4, and the 

 decollated shells from Funafuti 3 J mm. 



Two decollated specimens occurred to me in the Funafuti 

 lagoon. I have also taken the species between tide marks in Port 

 Moresby, British New Guinea. A Papuan specimen supplied 

 the material for the above account of the apex, missing in Funafuti 

 and New Caledonian examples. 



TRIFORIS THETIS, sp. nov. 

 XFig. 32). 



Shell small and slender. Colour uniform cinnamon-brown 

 except a patch of dark chocolate on the columella. Whorls 

 fifteen. Protoconch five whorled, the later three bicarinate, 



