236 MOLLUSCA. CEPHALOPODA. Orthoceua. 



number, the first the longest, the last produced into a conical neck, with a 

 round aperture. The colour brown. 



29. O. costata. — Subcylindric, straight, with four longitudinal 

 ridges. 



N. cos. Mont. Test. Brit. 199, t. xiv. f. 5— On the Kentish coast, Mr 

 Boys. 

 Length |th of an inch ; tapering little ; chambers subglobose, twelve in 

 number ; the ribs strong ; the neck of the last chamber shorter than in the 

 preceding species. A variety is recorded by Mont. ib. Supp. 84, t. xix. f. 2, 

 as having only five joints and seven ribs, anteally truncate; retrally termi- 

 nating in a [solid produced process. A second variety is likewise noticed at 

 the same page, in which the jomts are five in number. 



30. O. hicarinata. — Subcylindric, arcuated, the joints bicari- 

 nated. 



N. bicar. Mont. Test. Brit. Supp. p. 86 — Sandwich, Mr Boys. 

 Length ^th of an inch; joints eleven, globose, the ribs on the convex and 

 concave sides ; anteally the mouth is produced ; retrally there is a rounded 

 point. 



31. O. linearis. — Straight, compressed, the retral half with 

 faint oblique ribs. 



N. lin. Mont. Test. Brit. Supp. 87, t. xxx. f. 9 — Dunbar, Capt. Laskey. 

 Length |th of an inch, nearly linear ; the chambers are about fourteen in 

 number, the septa oblique ; the anterior end smooth, terminating in a pro- 

 duced mouth, the other rounded. 



** With spines or tubercles. 



32. O. spinulosa. — Spines numerous, reflected. 



N. spin. Mont. Test. Brit. Supp. 86, t. xix. £ 5 — Sandwich, Mr Boys. 

 Joints three, globose, the last produced to form the mouth. IVIontagu no- 

 tices a variety with eight subglobose joints which are tuberculated, which he 

 found in the Boysian cabinet. Its length ^'gth of an inch. 



*** Chambers smooth. 



33. O. recta. — Shell nearly straight, joints transverse, cham- 

 bers subcyhndric. 



N. rectus, Mont. Test. Brit. 197, t. xix. f. 4. 7 — Sandwich, Mr Boys. 

 Form a little tapering, length about ^'gth of an inch, with eight or nine 

 chambers. 



34. O. radicula. — Shell straight, joints transverse, chambers 

 subglobose. 



N. rad. Mont. Test. Brit. 197, t. vi. f. 4, and t. xiv. f. 6 — Sandwich. 

 " This species appears to be subject to very considerable variation with 

 respect to the extreme joint at each end, as well as in the number. In some 

 the ai)erture is extended to a conic point ; in others it is only a small round 

 opening on the extreme articulation, which is globose ; the smaller end, in 

 some, is rounded ; in others conic, pointed." 



35. O. suharcuata. — Shell subcvlindric, subarcuatcd, with 



