K« 



1879.] OECID.* OF THE 'CHALLENGER' EXPEDITION. 809 



seen with a septum of this character ; and, misled by this feature, I 

 at first considered it to be a specimen of C. reversum, Carp. ; but that 

 species belongs to his group Fartulum, with which the specimen in 

 hand has nothing to do. I believe it to be a new species. 



fo<i 5. C^CUM ATTENUATUM, n. Sp. 



" Sept. 8, 1874. Flinders Passage, Cape York. 7 fms. Nine 

 specimens. 



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

 nitida, subopaca, annulis numerosis crebris, hand seu vix expres- 

 sis, cincta, aperturam versus paululo latior vel dilatata. Aper- 

 tura vix obliqua, haud marginata, parum contractu, septo valido 

 mamillato-ungulato, margine laterali bicurvato, dorsali gibboso. 

 Length 1*8 mm. Breadth 0*4 mm. 



A very curious species, very small, conical, curved, long in pro- 

 portion 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. 



6. Caecum sepimentum, de Folin. 



July 1875. Reefs off Honolulu, 40 fathoms. Many specimens. 



Var. arcuata, de Folin. 



St. 172. July 22, 1874. Lat. 20° 58' S., long. 175° 9' E. 

 Tongatabu. 18 fms. Coral. Surf. temp. 75° F. One specimen. 



Sept. 28, 1875. Tahiti Harbour. 20 fms. Two specimens. 



De Folin, Les fonds de la mer, vol. i. p. 84, pi. vi. fig. 7. 



A species 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 Tonga- 

 tabu is somewhat broader and has thicker rings than those from 

 Tahiti. 



7. Caecum, n. sp. 



July 1875. Reefs off Honolulu. 40 fms. 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 equally broad and rounded with the rings. The 

 septum is regularly and hemispherically mamillated with a coarsely 

 tubercled surface. It seems to be a new species. 



8. Caecum chinense, de Folin. 



St. 186. Sept. 8, 1874. Lat. 10° 30' S.,long. 142° 18' E. Wed- 

 nesday Ishnd, Cape York. 8 fms. Coral-sand. Surf. temp. 

 7J°'- 2 F. Two specimens. 



De Folin, ■ Les Fonds de la Mer,' vol. i. p. 80, pi. ix. figs. 3, 4. 



52* 



