New British Freshwater Algae. By W. and G. 8. West. 151 
3. C. prjelongtjm Breb. (Babb. FI. Europ. Algar., iii. p. 130). 
Forma brevior Nordst. (Freshw. Alg. of New. Zeal, and 
Austr., p. 68, pi. iii. f. 22-24). 
Zygosporae globosae, glabrae. 
Diarn. zygosp. 40-46 g. 
Hab. In ditcb, amongst Vaucheria aversa Hass., near 
Ruislip Reservoir, Middlesex. 
4. C. gracile Breb. in Ralfs, Brit. Desm.. p. 221. 
Forma cum zygospora rectangulari, lateribus leviter 
retusis. PI. IV. fig. 47. 
Long, zygosp. 27 * 5 g ; lat. 20 g. 
Hab. Near Goring, S.E. Oxfordshire. 
The zygospore of this species is, as a rule, globose. 
5. C. Ehrenbergii Menegh. (Synops. Desm., p. 232 ; Ralfs, Brit. 
Desm., p. 166, t. 28, f. 2). 
Zygosporae globosae, membrana lamellosa, lamellis dif- 
fluentibus. 
IJiam. zygosp. (sine lamell.) 113-118 g . 
Hab. Wimbledon Common, Surrey, with zygospores in 
abundance, amongst Mougeotia mirabilis Braun. 
The conjugation appears to take place between two individuals 
which have just separated after division, and in which the younger 
semicells are but partially developed. (Of. note under Micrasterias 
dentieulata.) Moreover, the semicells do not come apart, but their 
contents pass through a perforated protuberance at the base of the 
younger semicells. 
6. C. parvultjm Nag. (Gatt. Einzell. Alg., tab. vi. fig. C, 2). 
Long, zygosp. 30-40 g ; lat. 26-34*5 g. 
Hab. Esher West End Common, and Mitcham Common, 
Surrey. 
The examples noticed of this always had elliptical zygospores 
which were occasionally surrounded by a very distinct gelatinous 
investment. 
7. C. trochiscosporum sp. n. PL III. figs. 16-20. 
Cl. minutum, semilunare, diametro 7-8-plo longius, ventre 
non tumidum, lateribus subparallelis ad medium, polos versus 
valde attenuatis curvatisque, apicibus subacutis; membrana 
glabra lutescens ; pyrenoidibus duobus semicellula unaquaque. 
Zygosporae oblongae et subrectangulares, lateribus bre- 
vioribus retusis, lateribus longioribus convexis et ad medium 
inflatis, angulis subrotundatis saepe tortae cum angulis duobus 
zygosporae in planitie perpendiculariter disposita ad planitiem 
angulorum duorum alterorum ; membrana glabra fuscescente. 
Lat. 8 * 6-9 * 5 ya ; apicibus inter se distantibus circiter 69 g ; 
long, zygosp. 23-28 * 5 g ; lat. max. zygosp. 18-22 g. 
M 2 
