486 Transactions of the Society. 



about equal proportions. Although the coiled neck cannot in anv 

 way be regarded as a specific distinction, it may be remarked that 

 the typical L. crenata always possesses this feature, and that it 

 becomes less marked the nearer the individuals approach L. semi- 

 striata. 



Of passage-forms towards L. semistriata may be enumerated the 

 following : — 



Lagenulina semistriata (Will.) Terquem, 1876, Anim. Plage de 

 Dunkerque, Part 2, p. 68, pi. vii. fig. 8. Lagena jioricla Terquem, 

 1882, Mem. Soc. Geol. France, ser. 3, vol. li. p. 26, pi. ix. rig. 9. 

 Oolina striaticollis d'Orbigny, 1843, Forarn. Amer. Merid., p. 21, 

 pi. v. fig. 14. Lagena semistriata (Will.) Bradv, 1884, Chall. Rept., 

 p. 465, pi. lvii. figs. 16, 17, 20. L. semistriata (Will.) Eg^er, 

 1893, Abhandl. k. bayer. Akad. Wiss., CI. II. vol. xviii. p. 327, pi. x. 

 fig. 39. 



Lagena semistriata Williamson, plate VIII. figs. 2, 3. 



Lagena striata var. fi semistriata Williamson, 1848, Ann. and 

 Mag. Nat. Hist., ser. 2, vol. i. p. 14, pi. i. figs. 9, 10. L. semistriata 

 (Will.) Wright, 1886, Proc. Belfast Nat. Field Club, 1884-85, A pp. 

 ix. p. 324, pi. xxvi. fig. 6, and L. semilineaia, p. 320, pi. xxvi. fig. 7. 

 L. semiornata Terquem, 1886, Bull. Soc. Zool. France, vol. xi. p. 320, 

 pi. xi.fig. 2. L. semistriata (Will,) Egger, 1893, Abhandl. k. bayer. 

 Akad. Wiss., CI. II. vol. xviii. p. 327, pi. x. fig. 34. L. semistriata 

 (Will.) Goes, 1894, K. Svenska Vet.- Akad. Handl., vol. xxv. p. 76, 

 pi. xiii. fig. 737. L. semidriata (Will.) Morton, 1897, Proc. Port- 

 land Nat. tlist. Soc, vol. ii. p. 117, pi. i. fig. 3. 



This form is very well represented, and most of the figured 

 varieties occur. 



There is nothing particularly wonderful in the variations of 

 beings existing under different circumstances ha lf-a- world apart, or 

 geological systems distant in point of time. These might be expected ; 

 but more interesting, because less accountable, are the variations of 

 creatures living generation after generation side by side in the same 

 locality, under the same conditions, and subject to precisely the same 



Explanation of Plate VIII. — continued. 



Fig. 16. — Lagena laevigata Keuss sp. var. acuta Reuss. X 100. a, Lateral aspect; 



b, oral aspect. 

 „ 17. „ multicosla Karrer sp. x 100. a, Lateral aspect; b, peripheral 



aspect ; c, oral aspect. 

 ,, 18. „ quadrata Williamson sp. var. x 100. a, Lateral aspect ; b, oral 



aspect. 

 „ 19. „ fasciala Egger sp. x 100. o, Lateral aspect ; b, oral aspect. 



„ 20. „ marginata Walker and Boys var. x loo. a, Lateral aspect ; 



b, oral aspect. 

 „ 21. „ marginata Walker and Boys var. x 100. a, Lateral aspect; 



b, peripheral aspect. 



