94 GENUS XIX. NA UTILUS. 



one chamber apparent and conical ; the former having 

 been successively effaced by the filling vip of the parti- 

 tions (see Belemnites, Park. Organ. Rem. 3. p. 122. t. 8. 

 f. 8 to 15). 



DiscoRBis. A spiral discoidal univalve ; the turns all con- 

 tiguous, uncovered, and perceptible ; the septa trans- 

 verse, whole, and frequent (see Park. Organ. Rem. 3. 

 p. 159. t. 11. f. 1). 



RoTALiTES. A convex, conical, spiral, multilocular, univalve, 

 slightly radiated beneath ; the opening marginal, trigo- 

 nal, and rather turning downwards (see Park. Organ. 

 Rem. 3. p. 160. t. 11. f. 2 and 3). 



Lentjculina. a sublenticular, multilocular, spiral univalve; 

 the external margin of the turns being complicated, the 

 septa reaching to the centre on each side : the septa en- 

 tire, curved, and standing out, on the upper and under 

 surface, like rays ; the aperture narrow, and projecting 

 beyond the penultimate turn (see Park. Organ. Rem. 3. 

 p. 161. t. 11. f. 4). 



LiTUOLA. A multilocular univalve, partly spiral^ the last turn 

 being straight at the end ; the chambers irregular ; plain 

 transverse septa, the last having several openings (see 

 Park. Organ. Rem. 3. p. 161. t. 1 1. f. 5 to 7). 



Spirolina. a multilocular shell, in part spirally convoluted ; 

 the turns contiguous, the latter ones straight ; the septa 

 transverse, and perforated by a tube (see Park. Organ. 

 Rem. 3. p. 161. t. 11. f. Sand 9). 



