central I, po.Mrrior valve II slils; treth v-rv .-harp, !"<! inat-d 

 Sinus Hat moderately deep and hnad, \\ith up to Hi teeth. 



Lengtli 80, hreadth 17 mill.; divei 



T, MKMA Sowerl.v. IM. II. ftgi, 28, I".), 30. 



Shell oval-oblong. smooth, sulicarinated ; valve- ncarlv 

 sul.ntrate ; lateral areas inconspicuous; maririn ['_ r mlle] smooth. 



Length 26, breadth 1 L'. 1 . mill. \o,r/,.) 



The smooth, narrow, .-lightly aiiLrulated species above de-rrib 

 of a blackish-brown color; the lateral areas an- not distinctly 

 marked except l>y rays ot'liirhtcr color in some specimen- on them, 

 and on the terminal valve>. (.sVw/>.) 



F'tlL-tnnd I*. (Sowb.) ; Ora),<f 7/./rW (U. S. Ex. Exped.) 



Chit nn nti-nttt Sowu. in Charlesworth's Magazine of Nat. Hi-t. 

 1840, p. 294 ; Conch. Illustr., f. 57, 58. REEVE, Conch. Icon., t. 1 7, 

 f. 103. GOULD, U. S. Kxpl. Kxped., p. 329, f. 415. 7 o// ///,/ ntrata 

 H. ct A. ADS., Gen. Kec. Moll, i, p. 474. ROCHKHIIUNK, I'olyplac. 

 Cap Horn, p. 138. T 7 . bcetica CPR., 3/N. <,lim. 



I have not seen this species. Carpenter writes: Mucro more or 

 less elevated, tumid behind. Inside having 8 slits in the anterior, 

 1 in the middle and 12 in the posterior valve; teeth acute, outside 

 and at the edge silicate, scarcely pectinated; sinus moderate, Hat, 

 with i:>-20 denticle-. 



Hutton reports this species from Macquarie Island, X. /., but 

 says: " Our species agrees very well with Reeve's figure, but not 

 with hi.s description. The anterior terminal area is distantly 

 radiately ribbed, and the lateral areas are sometimes defined by a 

 single rib. The umbone of the posterior valve is more posterior 

 than in the drawing, and the valves are of a uniform hrown color. 

 The mantle is of the same color as the valves." These characters 

 seem to me to indicate a distinct species, which may he called 

 /'// 



T. SWAINSONI Sowerby. PI. 43, figs. 41, 42. 43, 



Shell oval, moderately or decidedly elevated, somewhat earinated. 

 the side-slopes nearly straight. < I round-color li^ht pinki>h-l>uH'. 

 /minted all over with n mult if ml- r rrtl-hroivn linen, < 



t the beaks; often havinir some valves striped at or on each side of 

 the ridire, or more or le>s completely covered with dark n-d-lro\\n. 



Lateral areas little raised, xo////^,>'</ "/'/// ufn,,,t s 



