434 



allelis ; apice obtusissimo, lato, ad latus quadrat o : oper- 



culo ? . . . 

 Long. -068, lat. -009— '012. 

 Hub. Port Elizabeth {Bean). Mus. Brit. 



Three specimens were found, differing from all other known 

 species in the shape of the plug. This, on a side view, has parallel 

 sides with a somewhat rounded top ; the apes, however, is at the 

 end of one of the straight sides. The shell resembles B. glabra in 

 the non-contraction of the aperture. The texture is in some parts 

 slightly diaphanous, but opake behind the mouth. It may be a 

 Brochina. 



34. CAECUM REVERSUM, Cpr. 



C. (Fartulum) t.jun. " C. dextroverso" simili, sed septo sub- 

 convexo ; mucrone reverso, semicylindraceo, arcuato, aperturam 

 versus convexo, dorsum versus concavo ; t. adult a ? . . . : oper- 

 culo 1 . . . 



Long. -048, lat. -012. 



Hab. Mazatlan, 1 young sp. off Spondylus. Mus. Brit. 



Maz. Cat. p. 329. 



The plug is unique ; the mucro resembles a small Ccecum lying on 

 the slightly swollen surface, with its horns towards the back, and its 

 back adjoining the front of the shell. 



35. Cecum teres, Cpr. 



C. (Fartulum) t. elongata, tereti, longitudinaliter interdum sub- 

 angulata ; septo mucronato ; mucrone subelongato, obtuso ; 

 margine laterali subreeto : operculo vix concavo. 



Test. jun. long. -045, lat. -012. 



Test, adult, long. -115, lat. '017— -027. 



Hab. Mazatlan, very rare. Mus. Brit. &c. 



This shell has the shape of Elephantulum without the ribs, a ten- 

 dency to which, however, sometimes appears in slightly-marked 

 angles. 



36. CAECUM MAMILLATUM, S. Wood. 



C. (Fartulum) t. tereti, solida ; apertura haud declivi, tumente ; 



septo mucronato, mucrone dactyliformi ; margine laterali valde 



concavo. 

 Variat mucrone parvo, subtumente. 

 Long. -15, lat. -023— -033. 

 Hab. Sutton, Cor. Crag, abundant. Mus. Brit. &c. 



C. mammillum, S. Wood, Cat. 1842. 



C. mammillatum, S. Wood, Crag. Moll. p. 116, pi. 20. f. 4 a, c ; 

 ?-f f. n a (rubbed). 



Ado\. = Ccecum m. var. subulatum, S.Wood, loc. cit. f. 4 b. 



Jun. = Ccecum (?) incurvatum (?), S.Wood, loc. cit. p. 1 1 7, f. 7 a, b; 

 (non Serpula incurvata, Walker). 



