45 



Cttherea alternata. Cyth. testd subrotnndato-trigond, Uneis con- 

 centricis elevatis acutis frequentibus ornatd, albd spadiceo radiatd ; 

 ared dorsali vel posticd lunuldque spadiceo -violaceis ; intus albd, 

 vmbones versus spadiceo-violaceo obscure nebulosd ; limbo interna 

 leevi : long. 1"4, lat. 0"8, alt. 1"2 poll. 

 Hab. ad Columbiam Occidentalem. (Monte Christi.) 

 This species was dredged up in sandy mud at a depth of seven 

 fathoms. The size of the specimen is ratlier less than that of the pre- 

 ceding. — W. J. B. 



Cttherea tortuosa. Cyth. testd obliqu'i cordatd,postice sublobatd, 

 Uneis frequentibus subconcentricis obtusis pqstic'h irregularibus , 

 albd umbones versus subspadiceo-albd : long. 16, lat. 0"85, alt. 

 1-2 poll. 



Hab. ad Panamam, et ad Xipixapi. 



Var. testa roseo rufoque pulcherrime subradiatim pictil. 



Lamarck refers to no figure for his Cyth. albina, but only says that 

 it has some likeness to the Pectunculus figured in Lister's Conchology, 

 t. 263, /. 99. Part of Lamarck's description would apply to the 

 shell now before me, but the term " striis exiguis" is inapplicable to 

 the blunt and coarse lines with which the shell under description is 

 marked concentrically, and as there is no notice taken of the posterior 

 sublobation, I must conclude that Lamarck's Cyth. albina is not my 

 Cyth. tortuosa. 



Dredged up from sandy mud at a depth of six fathoms. — W. J. B. 



Cttherea affinis. Cyth. testd ovato-oblongd, planiusculd, Uneis 

 distantibus elevatis subacutis concentricis, albente violaceo ra- 

 diatd, postice vix sublobata ; ared posticd violaced, lunula pallidd- 

 intus albd, limbo interna leevi; epidermide fused tenui : long. \Q, 

 lat. 0-7, alt. I- 1 poll. 

 Hab. ad Colombiam Occidentalem. (Xipixapi.) 

 This species, which approaches the last, differs from it in the fol- 

 lowing particulars. The shell is much flatter, the elevated, regular, 

 concentric, somewhat sharp lines are much more distant, (especially 

 as they recede from the umbones,) than the irregular, close-set, blunted 

 lineations, almost amounting to rugosities, of Cyth. tortuosa. There 

 is an approach to lobation towards the dorsal or posterior border ; 

 but it is not nearly so strongly marked as in Cyth. tortuosa. Still it 

 may be a variety of Cyth. tortuosa. 



Dredged up from sandy mud at a depth of ten fathoms. — W. J. B. 



Cttherea Dione, varr. 



Though varieties of this species have, for a long time, been known 

 in this country, I am not aware that they have ever been recorded. 

 ITie descriptions of Linnaeus and Lamarck and the figures quoted by 

 them, apply to the variety found in the West Indies, which is com- 

 paratively small with the lamella high and sharp and the spines close- 

 set and short, the prevailing tinge of the shell being of a somewhat 

 vinous or purplish flesh-colour. A dark-coloured long- spined variety of 

 this and a white one, also with long spines, the spines in both being 

 very close-set, were dredged up from sandy mud at a depth of nine 

 fathoms at Salango in West Colombia. 



