490 GASTROPODA. [Pectinibranchia. 



pyriform, angled above, with, a long curved canal ; outer lip fairly 

 thick, convex, sometimes plicate within, with a deep sinus on the 

 carina ; columella sinuous, with an oblique thickening opposite the 

 fascicle of the beak ; inner lip thin, drawn out to a fine point on the 

 edge of the canal, broadly spreading over the body above. 



Distribution. California, Philippines. East Africa, Australasia. 



Fossil in the Tertiary from the Eocene. 



The type is from the Pliocene of Italy. 



KEY TO SPECIES. 



A. Suture simple, not distinctly margined. 



a. Spire-whorls with 3 prominent keels . . . . . . albula. 



b. Spire- whorls with 1 slightly nodulous spiral rib at the shoulder, 



the latter axially costate ; 2 narrow spiral grooves near 



the suture below . . . . . . . . Cheesemani. 



c. Spire-whorls with a rounded keel at the middle, and 



numerous spiral threads below ; suture canaliculate . . engonia. 



B. Suture distinctly margined. 



a. Shell very small ; spire-whorls with 3 spiral cords, the 



uppermost feeble ; distinct retrocurrent and flexuous 



axial threads . . . . . . . . . . gratiosa. 



b. Shell moderately large ; spire-whorls with a row of about 



16 prominent tubercles . . . . . . . . nodilirata. 



1. Bathytoma albula, Hutton, 1873. Plate 21, fig. 16. 



Pleurotoma albula, Hutt., C.M.M., 12. Drillia albula, Hutt., J. de Conch., 

 xxvi, 17. Pleurotoma albula, Hutt,, M.N.Z.M., 43 ; P.L.S. N.S.W., x, 

 116 ; Plioc. M., 49, pi. 6, f. 22. Surcula albula, Hutt, : Suter, T.N.Z.L, 

 xxxi, 68 ; Index, 71. Baihytoma albula, Hutt. : Suter, J. Mai., xii, 73. 

 Pleurotoma antipodum, E. A. Smith, A.M.N.H. (4), xix, 1877. 491 ; 

 M.N.Z.M., 43. 



Shell small, fusiform, spirally ribbed, with a short canal and twisted 

 colurnella. Sculpture : Spire-whorls with a prominent smooth spiral 

 rib at the lower third of the whorls, a smaller rib below the suture and 

 one above it, the latter sometimes split into 2 fine threads, the inter- 

 space between the first and second rib, which contains the crescent- 

 shaped growth-lines of the sinus, with a fine spiral thread ; body- 

 whorl with about 15 spiral line below the carina, usually stronger and 

 finer threads alternating ; they are fine and close on the fascicle of 

 the beak ; the somewhat irregular fine growth-lines are distinct in 

 the shallow grooves. Colour pinkish-brown, dead shells white. Spire 

 acuminate, high, conic, a little higher than the aperture. ProtoconcJ, 

 conical, of 2 smooth convex whorls, the nucleus slightly lateral. 

 Whorls 7 to 8, first slowly increasing, carinate, concave above and 

 below the keel ; base somewhat contracted. Suture lightly im- 

 pressed. Aperture pyriform. angled above, narrowed below to a 

 rather short recurved canal, its base not notched. Outer Up angled 

 above, convex below the carina, contracted toward the canal, a fairly 

 deep rounded sinus just above the keel in the excavation between 

 the first and second ribs, which, on the body-whorl, is sometimes 

 adorned with 2 or 3 fine spiral threads. Columella slightly excavated, 

 twisted below, and with a low fold opposite the fascicle. Inner lip 



