150 
Transactions of the Society. 
the descriptions of many hitherto unobserved zygospores of Desmids, 
and the descriptions of many new species, as well as the enumeration 
of some species as yet unrecorded for the British Isles. 
Class Confer voide/E Isogah^:. 
Order Confervace.e. 
Genus Conferva (Linn.) Link ; Wille. 
1. C. undulata sp. n PI. III. figs. 32, 33. 
C. cellulis cylindricis, diametro 2-3-plo longioribus ; mein- 
brana valida undulata, cellula unaquaque ad marginem 5-7 
undulata ; ad septa latioribus et membrana crassiori ad 
partem periphericam septi. 
Crass, fil. 6-9*5 fi; long. cell. 15-25 ya. 
Hah. Ogden Clough, W. Yorks.; Helvellyn, Westmoreland. 
We found this some time ago in the English Lake District, but 
it was not examined until after preseiwation ; for this reason it was 
put aside until living material might be available. Decently we 
found the plant again from the above-mentioned Yorkshire locality ; 
the examples were a little smaller than those from the Lake District, 
but otherwise precisely identical with them. 
Class Conjugate. 
Order Desmidiace.®. 
Genus Closterium Nitzsch. 
2. C. lanceolatum Kiitz. (Ralfs, Brit. Desm., p. 163, t. 28, f. 1). 
Zygosporae subglobosae vel ellipticae, glabrae. 
Diam. zygosp. 81-104 yu. 
Hah. Epping Forest, Essex. 
Plate IV. 
Fig. 84. — Cosmarium pseudoprotuberans Kirchn. x 520. Zygospore. 
„ 35. „ Iseve Rabh. x 400. Zygospore. 
,. 36. — Staurastrum margaritaceum Menegh. x 520. Zygospore. 
„ 87. „ corniculatum Lund, x 520. Zygospore. 
„ 38. — Cosmarium lusitanicum West, x 400. With zygospore. 
39. — Staurastrum sibiricum Borge forma trigona. x 520. 
„ 40. — Xanthidium Smithii Arch. var. variabile Nordst. x 520. Zygospore. 
„ 41. — Cosmarium confusum Cooke var. regularius Nordst. x 400. Zygospore. 
42.— Xanthidium antilopaeum (Breb.) Kutz. x 400. Zygospore. 
„ 43, 44 .—Penium cuticulare sp. n. x 520. 43, zygospore. 
„ 45. — Cosmarium inconspicuum sp. n. x 520. With zygospore. 
„ 46. — Staurastrum Kjelmanni Wille var. rotundatum var. n. x 520. 
„ 47. — Closterium gracile Breb. x 400. Abnormal zygospore. 
„ 48. — Staurastrum suborbiculare sp. n. x 400. 
„ 49. „ Picum sp. n. x 520. 
„ 50,51. ,, micron sp. n. x 625. 
tt 52. „ cuspidatum Breb. var. divergens Nordst. x 400. Zygospore. 
53-56. „ brachiatum Ralfs. x 400. Abnormal states of division. 
,, 57. — Cosmarium canaliculatum sp. n. X 625. 
„ 58. — Oscillatoria splendida Grev. var. attenuata var. n. x 520. 
