KELLIA. 225 



1. Kellia suborbicula'ris #, Montagu. 



My a saborbieularis, Mont. Test, Brit. p. 39, tab. 26. f. 6. K. suborbicularis, 

 F. & H. ii. p. 87, pi. xviii. f. 9, 9 a & 9 b, and (animal) pi. O. f. 4. 



Body white and nearly transparent : mantle protruding be- 

 yond the shell in front, and having its margin fringed with a 

 few thornlike or triangular tentacles : incwrent tube varying 

 in length and diameter even in the same individual ; its oriiice 

 plain, but uneven : excurrent tube short : gills pale yellow and 

 striated : lips thick, strong, and coarsely striated : foot com- 

 pressed, flexible, and hyaline. 



Shell usually globular, but sometimes inclined to an oval or 

 triangular outline, ventricose, rather thin, and more or less 

 glossy: sculpture, distant lines of growth, and close-set and 

 irregular concentric striae, besides some slight longitudinal 

 lines : colour milk-white, with a faint tint of yellow : epidermis 

 thin and beautifully iridescent: margins somewhat truncate 

 but obliquely rounded at the larger or posterior end, a con- 

 tinuous curve being formed by the ventral and anterior sides : 

 beaks circular and calvciform, incurved and twisted towards 

 the anterior or smaller end, close together, but not contiguous ; 

 they are placed nearly in the centre of the dorsal margin, and 

 there is a depression or incomplete lunule formed below them : 

 hinge-line curved, occupying nearly one-third of the circum- 

 ference : cartilage triangular, yellowish-brown, attached to the 

 hinge-plate close to the inner margin of the dorsal side, and 

 doubled on itself : hinge-plate narrow, but strong : teeth, in the 

 right valve two strong laterals, the one on the anterior side 

 being at first erect and resembling a cardinal tooth, and then 

 (as in Montacutaferruginosa) becoming laminar and attenuated, 

 that on the posterior side being obliquely triangular ; in the left 

 valve a recurved cardinal tooth, and two laterals similar to 

 those in the other valve, the cardinal and anterior lateral form- 

 ing a double tooth for the reception of the corresponding lateral 

 in the right valve ; dental sockets deep : inside like frosted 

 silver, with a slight prismatic lustre : pallial scar indistinct : 

 muscular scars large and conspicuous. L. 0*4. B. 0-45. 



Var. lactea. Shell somewhat compressed and oval, of a 

 thinner texture and rather more glossy ; front margin nearly 

 straight, and dorsal margin raised more to a level with the 



* Nearly globular. 



L O 



