OF CONCHOLOGY. 



137 



spire, directed backwards, and the sutural a second accumbent 

 on and crossing the spire, and recurved towards the left and back- 

 wards ; angular and median emitting single recurved spines ; 

 postsinual unarmed ; lobal emitting a large recurved spine in 

 advance of the middle of the ante-sinual lobe. 



Aperture ungniform, contracted behind by the development of 

 longitudinal callous ridges, which are almost applied on each 

 other, the columellar being outermost. 



The two species may be briefly distinguished as follows : 



1. Harpago chiragra, Adams f. ex Linn. 



Stromhus cliiragra^ Linn,, Syst. Nat. ed. 12, p. 1207. 

 Ptcrocera chiragra^ Lam,, Hist. Nat. An. sans Vert. ed. 2, ix, 



p. 675, Reeve, Mon, Pterocera, sp. 2, 

 Pterocera [Harpago) chiragra, Morch, Cat. ^oldi, i, p. 60. 

 Harpago ehiragra, Ad. f. Gen. Moll, i, p. 261. 



Fascicles, angular tuberculated, others almost unarmed, ante- 

 sinual with a compressed tubercle near the base of the digitation ; 

 lips rosaceous, with very faint and almost obsolete wrinkles ; 

 sutural digitation with a canal open at base, the outer border 

 being bent outwards and attached above the angle of the body 

 whorl, on which the digitation is chiefly bent and accumbent. 

 Large. 



Hab. — Society Islands. 



2. Harpago rugosa, ex Sowerby. 



Pterocera chiragra^ part Lam., Hist. Nat. An. sans Vert. ed. 



2, ix, p. 675 (Syn. part ; not desc.) 

 Pterocera rugosa^ Sowb., Thes. Conch, part 2, pi. 11, f. 9, 10. 



Keeve, Mon. Pterocera, sp. 6. 

 Pterocera [Harpago) arthritiea, Morch, Cat. Yoldi, p. 60. 

 Harpago arthritieus, Ad. f. Gen. Moll, i, p. 261. 



Fascioles, except sutural and ante-sinual, with prominent tu- 

 bercles ; ante-sinual smooth ; lips with very prominent white 

 wrinkles, contrasted strongly with the deep purplish or blackish 

 ground; basal posterior digitation with its canal closed by the 

 reflection of its margins, and accumbent on the middle of the 

 spire. Size moderate. 



Hab. — Eastern seas. 



§ 6. Extinct Associates. 



To the genus Pterocera have been referred numerous species 

 by various authors, most of which, however, have been success- 



