278 CARDIIDiE. 



5. C. exi'guum*, Gmelin. 



C. exigmtm, Linn. Syst. Nat. (ed. Gmel.) p. 3255. 6". pygnueum, F. & H. 

 ii. p. 29, pi. xxxii. f. 8, and (animal) pi. N. f. 2. 



Body triangular and much truncated at the posterior side, 

 yellowish-white : mantle plain-edged in front, and fringed 

 with numerous white filaments about the bases of the siphonal 

 tubes : incurrent (or branchial) tube the larger of the two, and 

 surrounded by a border of about ten filaments, with as many 

 or more tawny streaks radiating from it ; there is also a tinge 

 of tawny or orange around the orifice of the smaller or excur- 

 rent tube ; both are nearly sessile : foot long, cylindrical, and 

 large in proportion to the body ; its base is tinged with tawny, 

 the rest being white. 



Shell obliquely triangular, exceedingly gibbous, solid and 

 opaque, usually of a dull hue, and never so glossy as that of 

 the last species : sculpture, 20 or 21 ribs, which are at first 

 sharp and angular but afterwards become compressed and 

 broad, especially in front ; the ribs are in young specimens 

 more or less covered with small white tubercles, which are 

 not formed in the adult except on the anterior side ; the fur- 

 rows, which are very narrow, are crossed and indented by 

 numerous regular, oval punctures : colour yellowish or dirty- 

 white, sometimes variegated by purplish-brown streaks or 

 blotches, which are more visible on the posterior side, occa- 

 sionally tinged with pink: epidermis fibrous and often thick, 

 yellowish- brown of different shades : margins bluntly angular 

 on all sides except in front, where there is a contraction simi- 

 lar to that in G. tuberculatum, causing this side to be very 

 gently curved, and not so much rounded as in most other 

 species ; the angle or ridge separating the posterior side is 

 very conspicuous and increases the gibbosity of the shell : 

 bealcs very small, not contiguous, inclining a little to the ante- 

 rior side, and placed very much nearer to it ; beneath them on 

 this side is a deep and heart-shaped or lanceolate ribless de- 

 pression, more like a lunule than the similar mark in any of 

 the preceding species, and having slightly projecting lips : 

 ligament short and sunken, cylindrical, yellowish-brown: 

 hinye-line slightly curved : hinge-plate thick, reflected, occupy- 

 ing scarcely one-fourth of the circumference : teeth, in the 

 right valve two cardinals, the posterior of which is much the 



* Little. 



