Nummulita. MOLLUSCA. CEPHALOPODA. 233 



15. L. concamerata. — Surface of the chambers glossy and 



smooth. 



Serpula con. Mont. Test. Brit. Supp. 160. 



This species, found by Montagu on the coast of Devon, is thus described : 

 " Shell suborbicular, compressed, flat beneath, slightly convex above, and of 

 a subpellucid white colour, with three irregular volutions, and numerous dis- 

 similar concamerations ; the exterior whorl has about nine glossy and tumid 

 cells, of unequal size, but usually a larger and smaller alternate. Diameter 

 half a line. This very minute species is at once distinguished from S. lobata, 

 by possessing much more numerous and infinitely more minute chambers, 

 which are smooth and glossy, and not of that frosted appearance the lobata is 

 invariably found to be, when examined by a microscope." The author whom 

 we have quoted, was inclined to consider the adhesion of these species to co- 

 rallines and other bodies as identifying them with the genus Spirorbis. They 

 are not (at least the Lobatula vulgaris), however, cemented, but seem to ad- 

 here by the intervention of some animal matter. 



Gen. NUMMULITA. — Lenticular, with an internal dis- 

 coidal multilocular spire, divided into numerous chambers 

 by transverse imperforated septa, and covered by several 

 plates, the wall of each turn being complicated, extended 

 and united on each side to the other discs. 



1. N. laevigata. — Convex on both sides, and smooth. 



Lamark, Syst. Vert. vii. 629. Park. Org. Rem. iii. 152. t. x. f. 13. — In 

 the London Clay, Hubbington Cliff'. 



Gen. VI. VERMICULUM.— Chambers gibbose, the mouth 

 alternately at the opposite ends of the axis. 



16. V. hitortura. — Mouth compressed, with a simple tooth 

 attached to the proximal side. 



Serpula seminulum, Linn. Syst. i. 1264 — Serp. subovalis umbilico per- 

 vio, Walk. Test. Min. t. i. f. 1 — Serp. ovalis, Adams, Linn. Trans, v. 



p. 4. t. i. f. 28, 29, 30.— Ver. in. Mont. Test. Brit. 520 Flem. Wern. 



Mem. iv. 564. t. xv. f. 3 — Common on corallines and old shells. 



Size about ^th of an inch, a little compressed, the external margin sub- 

 acute. Three chambers are usually visible on one side, and four on the 

 other, slightly striated across with the line of separation distinct. The tooth 

 is a triangular thin plate, a little recurved at the tip, and so persistent as 

 frequently to remain after the outer side of the chamber has been destroyed. 



17. V. oblongum. — Mouth round, with a pedunculated fork- 

 ed tooth. 



Mont. Test. Brit. 522. t. xiv. £ 9. Flem. Wern. Mem. iv. 565. t. xv. f. 4. 

 — Common. 



Bather less than the preceding. Three chambers are usually visible on 

 one side, and two en the other ; in the former the middle chamber is par- 

 tially embraced by the outer ones, so that a shallow depression is formed at 

 the outside of the line of junction. On the other side of the shell a similar 



