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
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