PECTUNCULUS.— Plate VI. 



Hab. St. Elena, South America (found in sandy mud at 

 the depth of from six to eight fathoms) ; Cuming. 



A very solid broadly ribbed shell, so peculiarly con- 

 tracted towards the umbones that the hinge almost de- 

 scribes an angle. 



Species 32. (Mus. Cuming.) 



Pectuncultjs castaneus. Pect. testd orbkulari, sub- 

 tequilaterali, longitudinaliter costatd, costis crebris, 

 striatis ; albd, castaneo maculatd, maculis in zonis 

 undulatis transverse dispositis. 



The chestnut-coloured Pectunculus. Shell orbi- 

 cular, nearly equilateral, longitudinally ribbed, ribs 

 numerous, striated ; white, spotted with chestnut, 

 spots arranged in transverse waved zones. 



Lamarck, Anim. sans vert. (Deshayes' edit.), vol. vi. 

 p. 493. 



Area variegata, Chemnitz, Conch., vol. vii. pi. 57, 

 f. 562. 



Hab. West Indies. 



I have not met with any specimen of this species so 

 richly variegated with colour, as that represented by 

 Chemnitz. 



Species 33. (Mus. Cuming.) 



Pectunculus obliqtjus. Pect. testd transversd, oblique 

 ovatd; albido-ruf escente , maculis cuspidiformibus spa- 

 diceis profuse pictd ; intus nig errimo -fused ; umbo- 

 nibus centralibus. 



The oblique Pectunculus. Shell transverse, obliquely 

 ovate ; ruddy white, profusely painted with red- 

 dish-brown arrow-head-shaped spots ; interior very 

 dark brown ; umbones central. 



Reeve, Pro. Zool. Soc, 1843. 



Hab. Swan River; Lieut. Collie. 



The whole of the inside of this shell, with the excep- 

 tion of the anterior margin and muscular impression, is 

 of a very deep blackish brown. 



Species 34. (Mus. Cuming.) 



Pectunculus Tellin-eformis. Pect. testd ovatd, trans- 

 versd, subdepressd, radiafim costatd, costis subobso- 

 letis ; albidd, antie'e et superne carneo-fusco tinctd ; 

 intus subfuscd, postice albicante ; umbonibus vix obli- 

 quis. 



The Tellina-shaped Pectunculus. Shell ovate, 

 transverse, rather depressed, radiately ribbed, ribs 

 almost obsolete ; whitish, stained anteriorly and 

 around the ventral margin with fleshy brown ; in- 

 terior rather brown, posteriorly whitish ; umbones 

 slightly oblique. 



Reeve, Pro. Zool. Soc, 1843. 



Hab. Rio Janeiro ; Miller. 



This shell differs from the preceding in being more 

 transverse, and faintly ribbed ; the interior is not so 

 dark, nor does the outer surface exhibit the least indica- 

 tion of any spots or other dark marks. 



Species 35. (Mus. Cuming.) 



Pectunculus tenuicostatus. Pect. testd orbiculari, 

 subventricosd, subtilissinie costatd, costis quasi f lis, 

 numerosis, interstitiis epidermide lineariter insertd • 

 fuscescente, costis pallidioribus ; umbonibus subcen- 

 tralibus. 



The thin-ribbed Pectunculus. Shell orbicular, ra- 

 ther ventricose, very finely ribbed ; ribs like threads, 

 very numerous, with the epidermis inserted in lines 

 in the interstices ; brownish, ribs paler ; umbones 

 nearly central. 



Reeve, Pro. Zool. Soc. 1843. 



Hab. Australia. 



The valves of this shell are entirely covered with 

 beautiful thread-like ribs, and the interstices are filled 

 with fine roots of epidermis arranged in from three to 

 four rows. 



