Mr. J. G. Jeffreys on British Mollusca. 39 



assumed by the cell-contents (the rest of the cells in this as well 

 as in the other filaments are not filled up, because the disposition 

 of the contents in all is much alike) ; d, annular striae indicative 

 of a spore-cell before inflation. 



Fig. 2. (Edoc/onium dioicum. Male filament : a, a, a, antheridia, or groups 

 of annular cells producing spermatozoids. Vide fig. 8. 



Fi(/. 3. CB. diandronites, H. J. C. (nov. sp. ?) : a, spore-cell previous to 

 the formation of the micropyle and resting-spore ; b, ditto, after 

 their formation ; c, c, c, annular cells, two in each group, bearing 

 each a single spermatozoid. 



Fig. 4. (E. triandronites, H. J. C. (nov. sp. ?) : a, spore-cell before the 

 formation of the micropyle and resting-spore ; 6, ditto, after their 

 formation ; c, c, c, annular cells, three in each group, producing 

 spermatozoids. 



Fig. 5. Resting-spore of CE. dioicum, with the spermatozoids trying to 

 efffect incorporation. 



Fig. 6. Ditto, with three spermatozoids fixed, apparently in three different 

 degrees of arrested incorporation. 



Fig. /. Diagram of resting-spore, &c., of CE. dioicum, to show — a, cell- 

 wall of filament and spore-cell ; b, protoplasmic sac or internal 

 layer; c, outer coriaceous or thick covering of resting-spore; 

 d, inner or thin layer of ditto ; e, contents, consisting of starch- 

 cells (?), protoplasm, chlorophyll, and a few oil-globules. 



Fig, 8. Male filament of ditto, in dehiscence, showing — a, a, annular cells 

 bearing spermatozoids ; b, protoplasmic sac or inner cell-layer of 

 prematurely opened annular cell containing two spermatozoids, 

 each of which is again enclosed in its proper cell ; c, ditto, with 

 the latter ruptured ; d, d, spermatozoids escaping from their cells 

 direct. 



Fig. 9. Resting-spore of CE. diandronites, with three spermatozoids round 

 the micropyle, and one entering. 



Fig. 10. Ditto, representing the spermatozoid in the act of incorporation. 



Fig. 11. Ditto, after the incorporation, with the three remaining sperma- 

 tozoids still swarming round the micropyle. 



Fig. 12. Resting-spore of CE. triandronites, to show the beaded appearance 

 round its circumference. 



Fig. 13. Ditto of CE. dioicum, showing abnormal development of conical 

 cells : a, conical cell, containing fine muco-granular matter ; 

 b, ditto with ditto having passed into monads ; c, ditto, empty, 

 with the lid attached ; d, ditto, growing out from the opposite side. 



Fig. 14. Conical cell separate, with the lid opened, and the contents 



issuing enclosed in a delicate sac. 

 Fig. 15. Ditto, with the sac burst, and the contents issuing in the form of 



monociliated monads. 

 Fig. 16. Spermatozoid more magnified, to show its cilia. 



V. — Gleanings in British Conchology. 

 By J. GwYN Jeffreys, Esq., F.R.S. 



[With a Plate.] 



Being informed by Mr. Hanley, the surviving author of 'A 

 History of British Mollusca and their Shells,^ that it is not his 

 intention to publish a supplement to that excellent work, I will 



