RONGL. SV. VET. AKADEMIENS HANDLINGAR. 



BAND 25. N:0 5. 



Long. 24 — 28, lat. 44 — 54, lat. isth. 14 — 17, long. proc. 6 — 10 f*. Wallich 

 20—23, 31—48, » ? , » 5— 10«, Beng.Desm. 



p. 197. 



T. XVIII, f. 18; a b fronds in f. v., W. B. T. ad nat.; c, fronds in division 

 X 500; d. basal view; e. apical view; f. conjugation, sac formed; g, two empty fronds 

 with sac and young zvgospore; h (and d) fronds with parasitic epiphvtes; after Wal- 

 lich, X circ. 450. 



The zvgospore is oval, when mature covered with a thick smooth (colonrless?) 

 membrane, its diameters are 36 X 28 ,«. 



This genus, like Ancylonema Bergr. and Pagetophila Wittr., has the peculiarity 

 of consisting as yet of one species onlv. 



[Wallich, p. 197, appends a note upon the epiphvtes found by him, »The mu- 

 cous matrix in which the species of this genus are imbedded of t en exhibits a number 

 of pin like bodies, stuck, as it were, into everv part of the joint — the heads, which 

 are minute, oblong, granular, and of a rich green colour, being directed outwards. 

 These growths appear to be epiphytieal, and are seen also in the various forms of 

 Splicerozosma and Leuro7iema>-> (Spondylosiwm). »Their minute size renders any exa- 

 mination of their characters impossible. It may be mentioned, however, that they are 

 quite distinct from the delicate radiating lines frequently met with in the mucous 

 envelope of the majority of the Desmidiacese.» Cfr Archers notes, in Proc. Dubl. 

 Micr. Club, on Stria? in Desmid-mucus, Bacilli in mucous investments of Algae, and 

 on »Headed Bacteria»; the two latter in Q. Journ. M. Sci. respectively of pp. 105 — 6, 

 vol. XVI, 1876, and also pp. 237—240; the former in Annals N. H. ser. 5, vol. VII, 

 p. 341, 1881. These little epiphvtes have been placed by Gobi (Xotarisia p. 384, 

 1887) in a separate genus under the name of Peroniella (sec. De Toni. Sylloge Chlo- 

 roph. p. 630, who refers to a memoir on the subject by Gobi in Scripta Bot. Horti 

 Petrop. t. I. p. 1 — 18, tab. 1). De Toni considers the genus as inclining towards 

 Sciadium Al. Br.; he remarks, on P. hyalothecce Gobi, 'huc verisimiliter pertinent, 

 monente cl. amico O. Nordstedt in litteris, formae a cl. Wallich in Desm. of Bengal 

 p. 273, t. VII, f. 5 descripta? et illustratae quae in nonnullis Desmidiaceis Jiliformibus 

 ex Bengalia indicatae sunt.»] 



Gen. 24. Desmidium, Agardh. 



(Syst. Alg:, p. 15, 1824, sec. Wittrock, mut. char.; De Baky' Conj. p. 70, 18Ö8, Didymoprium Kim excl.) 



1. D. Swartzii, Agardh (Syst, Alg. p. 9, 1824, sec. Wittr.: Consp. ('rit. Diat. p. 56, 

 1830! Diatoma Swartzii Ag. in Svensk. Bot. vol. VII, t. 491, f. 1—3, 1812; Dec. 

 Alg. No. VIII; Synops. Scand. p. 118, 1817; Disp. Alg. Suec. p. 34, 1812!) 



a. typica. Apicibus semicellularum totaliter approximatis, in fila adpressis; »foramina» 

 nulla — ut in Ralfs Br. Desm. p. 60, t. IV, a b c d. 



Long. 14—15, lat. 34—39 //; (long. 15.2, lat. 36 ,u G. C. W.). 



b. minor. Wallich Mscr. No. 56. 



K. Sv. Vet. Akacl. Handl. Band 2:'). N:o :'». 19 



