— 171 - 



guished from the typical form by the reduced lobules of the lateral lobes 

 and the greater attenuation of each extremity of the polar lobe. It re- 

 ceives its name from its resemblance to those species of Micrasterias 

 which were at one time placed under TetrachastrUm. 



55. JW. rotata Ralfs in Ann. Mag. Nat. Hist. V, 1844, p. 299, t. VI, 

 f. 1; Brit. Desm. 1848, p. 71, t. VIII, f. 1. 



In stagnant water in the jungle. 



Area: Europe, N. and S. America. India, Singapore. Japan. 



Cosmarium Corda. 



56. C. pseiidopyramidatum Lund, in Nova Acta R. Soc. Scient. Up- 

 sala, ser. 3, VIII, 1871, p. 41, t. II, f. 18. 



Long. 54 // ; lat. 36//; lat. isthm. 11//. 

 Area: General in temperate and tropical climates. 



57. C. læve Rabenh. Flor. Europ. Algar. Ill, 1868, p. 161; Nord- 

 stedt in Öfvers. af K. Vet.-Akad. Förh. 1876, no. 6, p. 29, t. XII, f. 4; 

 G.S.West in Journ. Linn. Soc. bot. 1899. (Tab. nostr. II, fig. 14.) 



Long. 22 — 25//; lat. 16 — 19,5/* ; lat. isthm. 5,8 — 6,7// ; crass. 9 — 10//. 

 Zygosporæ angulari-globosæ, glabrae , angulis leviter incrassatis. Diam. 

 zygosp. 22 — 25//. (Tab. nostr. II, fig. 15— 16). 



This occured in enormous quantity on rocks in a riverbed and the 

 zygospores were abundant. We have previously described what we then 

 thought to be this plant in zygospore (cfr. West & G. S. West in Journ. 

 Roy. Micr. Soc. 1896, p. 154-5, t. IV, f. 35; West in Notarisia 1892, 

 p. 1502), but we can now definitely say that is was not. The Cosmarium 

 we described from Portugal as C. lœve with zygospores („zygosporæ glo- 

 bosæ' spinis brevibus numerosis truncatis bifidisve ornatæ") is certainly 

 not C. lœve Rabenh., but some other closely allied species with smooth 

 cells and a spiny zygospore. We are sure of this because we have now 

 obtained C. lœve Rabenh. in zygospore in such great quantity. 



Area: Europe, N. and S. America, E. and W. Africa. Madagascar, India, 

 Ceylon, E. Indies, New Zealand and Australia. 



58. C. pseudonitidulum Nordst. in Acta Univ. Lund. IX, 1873, p. 16, 

 t. I, f. 4. 



Long. 37//; lat. 25-//; lat. isthm. 7,5//; crass. 16 

 All the forms seen were very delicately punctate. 



In stagnant water in riverbed amongst Spirocjyra gracilis. Also among 

 Utricularia in riverbed. 



Area: Europe, Central China. 



59. C. obsoletum Reinsen in Abhandl. Senckenb. naturf. Gesellsch. 

 VI, 1867, p. 142, t. XXII DI, f. 1-4; in Abhandl. Naturhist. Gesellsch. 

 zu Nürnberg III, 167, p. 184, t. XII, f. 4. C. palustre Turner in Kongh 



