Freshwater Algse and Bchizo^hyeese, By A. W. Bennett. 7 
Micrasterias papillifera Breb., H. 
„ truncata Breb., H. 
„ „ Breb. var. tridentata n. var., H. 
Fig. 10. 
A variety with the lateral lobes tridentate instead of bidentate. 
Micrasterias crenata Breb., H, D. Figs. 11, 12, 
Two forms of this variable species. De Wiideman has shown 
(Bull. Koy. Soc. Belg., 1888 ; Obs. sur qnelques Desm., p. 2) how 
closely this species is linked with the preceding by intermediate 
forms. 
Micrasterias crux-melitensis Men., H. Fig. 13. 
The form observed (but only very rarely) of this rare and beautiful 
desmid in the New Forest bears a much closer resemblance to that 
which occurs in America (Wolle, Desm. U.S., t. xxxv. f. 3) than to 
any hitherto recorded from Great Britain, the lobing not being nearly 
so deep. The outline of the frond is very nearly circular, about 140 //, 
in length and breadth ; its surface is covered with small protuberances. 
The species has been gathered hitherto, in the south of England, 
as far as I am aware, only by Jenner. 
Euastrum oblongum Grev., H. 
„ crassum Ktz., H, D. 
„ CRASSO-HUMEROSUM n. var., D. Fig. 14. 
This interesting variety or possible hybrid is described at length 
elsewhere (‘ Annals of Botany,’ vol. iv. p. 171). 
* Euastrum pinnatum Ealfs, H. 
„ humerosum Ealfs, H, D. 
* „ ventricosum Lund., D. 
„ affine Ealfs, D. 
„ ampullaceum Ealfs, D. 
„ insigne Hass,, D. 
„ didelta Ealfs, H, D. 
„ cuneatum Jenn., H. 
„ ansatum Ealfs, H, D. 
„ circulare Hass., H, D. 
„ pectinatum Breb,, H, D. 
„ rostratum Ealfs, H. 
„ binale Ealfs, H. 
* „ erosum Lund., H, D. 
„ ornithocephalum Benn., H. 
Cosmarium quadratum Ealfs, D. 
* „ homalodermum Nordst., D. Fig. 15. 
Nearly circular in outline; length and greatest breadth about 
7 0 yu. ; two conspicuous protuberances on each half-cell. Bog-pools, 
