688 THE VOYAGE OF H.M.S. CHALLENGER 



but it is straighter, and the texture of the shell is different, exhibiting under the microscope fine 

 longitudinal striations. Though unable, from its imperfect condition, to offer a full description, the 

 specimen is so clearly a new species that I venture to attach to it the name I have given above. 



13. Ccecum angustum, n. sp., de Folin (PI. L. fig. 8). 



Station 186. September 8, 1874. Lat. 10° 30' S., long. 142° 18' E. Wednesday 

 Island, Cape York, North Australia. 8 fathoms. Coral mud. Surface temperature 77°"2 F. 



Testa minuta, subcylindrica, satis elongata, angusta, subflava, paulo nitida ; primum 

 sublsevis, super ultimam partem annulata, annulis baud prominentibus, sulcis vix profundis 

 angustis separatis. Apertura valde declivi, restricta, labro acuto. Septo mamillato 

 rugoso, ad dorsum inflato. 



Length, 0-067 in. Breadth, 0'012 in. 



At first sight the solitary specimen of this species seemed to be half-grown, but fuller examina- 

 tion proved it to be adult. This is indicated by the very oblique mouth, which forms an angle of 

 30° with the tangent to the dorsal slope ; still more distinctly is this implied by the contraction of 

 the mouth ; and, finally, for two-thu-ds of the length, the form of the shell is very cylindrical, 

 indicating that there has been no increase of breadth except on the first third, and even there it is 

 scarcely appreciable ; all this points to a shell which has reached its full development. The general 

 form is narrow and rather long ; its colour is yellow ; it is smooth on the first two-thirds ; on the 

 last thhd there are rings which are feeble, slightly rounded and approximate, the parting furrows 

 being narrow and shallow. The mouth-edge is sharp. The septum is mamillate, wrinkled, and 

 swollen toward the dorsal side. 



14. Ccecum eburneum, n. sp., de Folin (PI. L. fig. 9). 



Station 186. September 8, 1874. Lat. 10° 30' S., long. 142° 18' E. Wednesday 

 Island, Cape York, North Australia. 8 fathoms. Coral mud. Surface temperature 77° # 2 F. 



Testa minuta, parum arcuata, cylindrica, satis lata, haud elongata, nitida eboris con- 

 spectu, lsevis, transversim irregulariter strigata, aperturam versus infiata, dein normalis 

 et paululo restricta, subannulata. Apertura haud declivi, labro acuto. Septo mamillato, 

 parum prominente. 



Length, 0-087 in. Breadth, 0-02 in. 



This species, like most of the smooth Cascums which have a mamillate septum, is in form almost 

 cylindrical, and is brilliant, very faintly yellow, with the aspect of ivory. It is somewhat irregularly 

 transversely striate. Its essential distinguishing characteristic is a somewhat marked swelling rather 

 remote from the mouth towards which it again contracts, so as to present at the end nearly the 

 same diameter as at an earlier point. This swelling presents some three or four folds, or feeble 

 rings, close to the mouth, which is very slightly contracted, is not oblique, and presents a very sharp 

 edge. The septum is roundly mamillate, but very little prominent . 



[For species 15 and 16 see p. 680.] 



