684 THE VOYAGE OF H.M.S. CHALLENGER. 



2. Ccecum attenuatum, de Folin (Omctdm, PL II. figs. 9-11). 



Ccecum attenuatum, de Folin, Csecidse of the Challenger Expedition, Proc. Zool. Soc. Lond., 1879, 

 p. 809. 



September 8, 1874. Flinders Passage, Cape York. 7 fathoms. Nine specimens. 



Testa, quoad genus, mediocris, conica, arcuata, elongata, alba, parum nitida, subopaca, 

 annulis numerosis crebris baud seu vix expressis cincta, aperturam versus paululo latior 

 vel dilatata. Apertura vix obliqua, baud marginata, parum contracta. Septo valido 

 mamillato-ungulato, margine laterali bicurvato, dorsali gibboso. 



Length, 0'07 in. Breadtb, 0*016 in. 



A very curious species, very small, conical, curved, long in proportion to its breadth, slightly 

 glossy, opaque. It looks smooth ; but under a lens it appears ornamented with numerous close-set, 

 scarcely projecting rings. Towards the mouth the shell broadens a little and then contracts, thus 

 forming a peristome which is slightly oblique and has no ledge. The septum is enormous, and in 

 form is at once mamillated and ungulated. Its dorsal protuberance or hump, when looked at from 

 behind, rises in an equable curve from either side. 



3. Ccecum sepimentum, de Folin. 



Caecum sepimentum, de Folin, Les Fonds de la Mer, vol i p. 84, pi. vi. fig. 7. 



July 1875. Eeefs off Honolulu. 40 fathoms. Many specimens. 



Var. arcuata, De Folin. 



Station 172. July 22, 1874. Lat. 20° 58' S., long. 175° 9' W. Tongatabu. 18 

 fatboms. Coral mud. Surface temperature 75° F. One specimen. 



September 28, 1875. Tahiti Harbour. 20 fathoms. Two specimens. 



This is a species originally described from specimens dredged at Mauritius. The numerous 

 specimens from Honolulu are quite of the typical form. The var. arcuata is shorter and more bent. 

 The specimen from Tongatabu is somewhat broader and has thicker rings than those from Tahiti. 



4. Ccecum, n. sp. {Gmoidm, PL II. fig. 12). 



July 1875. Reefs off Honolulu. 40 fathoms. One broken specimen. 



Probably a third of the shell is broken away. It is ornamented with strong and pretty regular 

 rounded transverse rings, which are parted by hollows as broad and as rounded as the rings. The 

 septum is regularly and hemispherically mamillated with a coarsely tubercled surface. It seems to be 

 a new species. 



