Amplexus. MOLLUSCA. CEPHALOPODA. 251 



10. B. spinulosa. — " Depressed, undulations regular, every other one arm- 

 ed with two sharp spines; ;opening elliptical; curvature very gradual;" struc- 

 ture obscure Soiver. Min. Conch, t. ccxvi. f. 1 Green Sand, Blackdown. 



11. B. spiniger. — " Depressed; undulations many, slender; two rows of 

 sharp tubercles upon each side, those nearest the front largest ; curvature 

 gradual." — Sower. Min. Conch, t. ccxvi. f. 2. 



12. B. tuberculata "Depressed; undulations unequal, every third one 



largest, with two tubercles on each side, the lateral ones obscure ; curvature 

 gradual." — Sower. Min. Conch, t. ccxvi. £ 4, 5 — Chalk Marl, Folkstone. 



13. B. turgida "Depressed; front irregularly swelled ; undulations re- 

 gular, disappearing over the back ; two rows of obscure tubercles near the 

 front ; curvature rather sudden."— Soiver. Min. Conch, t. ccxvi. f. 6, — Chalk 

 Marl, Folkstone. 



14. B. nodosa. — " Nearly round, undulations regular; two rows of obtuse 

 tubercles upon the front, each tubercle placed upon two undulations ; aper- 

 ture obovate." — Sower. Min. Conch, t. ccxvi. £ 3. — Chalk Marl, Folkstone. 



15. B. pUcatilis " Slightly depressed, with numerous annular ridges ; two 



rows of large, equal, flat tubercles upon each side ; curvature gradual. — Sow- 

 er. Min. Conch, t. ccxxxiv. £ 1 — Chalk Marl, Warminster. 



Gen. AMPLEXUS. — Nearly cylindrical, divided into cham- 

 bers by numerous transverse septa, which embrace each 

 other with their reflexed margins. 



1. A. coralloides. — Tube irregularly bent, longitudinally striated ; margins 

 of the septa deeply reflected, and regularly plaited. The septa seem to have 

 no perforations Sower. Min. Conch, t. lxxii — Transition Limestone, Cork. 



[The following extinct species in the genera Nautilus, Nummulita, and 

 Orthocera, are here added, having been omitted at their proper places at 

 pp. 229, 233, and 238.] 



1. Nautilus expansus.- Subglobose, umbilicated, finely striated; umbilicus 

 small; sides of the aperture expanded — Soiver. Min. Conch, t. cccclviii. £ 1. 

 — Chalk Marl, Hamsey. 



2. N. biangulatus. — Discoid, subglobose, with'a large umbilicus, and a keel 

 upon each side; front rounded. — Sower. Min. Conch, t. cccclviii. £ 2. — In 

 Mountain Limestone, Bristol. 



3. N. globatus — Subglobose, smooth, umbilicated ; whorls few, inner ones 

 concealed, rather flattened on the front, rapidly increasing ; umbilicus deep, 

 with an angular margin ; aperture very wide, arched, with a deep sinus in 

 the front — Sower. Miu. Conch, t. cccclxxxi. — Probably my N. Wrightii is 

 identical with this species — From Cork. 



4. N. multicarinatus — Discoid, subglobose ; inner whorls half exposed in a 

 large deep umbilicus ; edge of the umbilicus angular ; front compressed with 

 several carinae on each side the middle. — Sower. Min. Conch, t. cccclxxxii 

 £ 1, 2 Transition, Limestone, Cork. 



5. N. carinatus — " Discoid, subglobose ; inner whorls half exposed, in a 

 large umbilicus ; a keel in the middle of each side, and two ridges between 

 it and the flattened front." — Sower, t. cccclxxxii. £ 3. — Identical with N. ex- 

 cavatus already described. 



