I ' 



PEDIASTRUM. 



?27 



Family : FLEUROCOCCACE& 



Genus: Urococcus Kiitz. 





• 175. Urococcus tropicus sp. n. (PI. xi, figs. 17—21). 



Cellulse vegetative magnse, subsphaericae, ellipsoide*, ovoide*, pyriformet rel 

 subirregulares ; membrana cellularum crassa et conspicue lamellosa, valde et exoentrioe 

 incrassata ; cellule paucae (usque ad 8) coloniaui formantes, cellulis irregulariter diipotiti* 



et stipitatis, stirpibus crassis irregularibus lamellosis et plus minusvo confimntib 



Chromatophoris vaide granulosis, cum pyrenoidibus 1 vel 2 inclusis. 



Propagatio cellularum divisione in omnes directiones. 



Long. cell. 19-36-5/*; lat. cell 13-33/*; crass, membr. cell. 3-6 M ; diam. colon. 

 usque ad 158/t. 



Hab. — In the Kan-gyi at Mudon (No. 24505), 



This Alga is characterized by the thick-walled cells, which are supported fiinglv or in small 

 colonies by hyaline stalks. These stalks are gradually developed and are very firm. They at* 

 conspicuously lamellose and more less irregular at the margin. The celU multiply by diiitioc 

 which may occur in any direction, but no colonies were observed consisting of more than eight 



cells. The cells soon break away from the small colonies, and each proceeds by cell-division and 



the growth of the tough hyaline stalks to build up anew colony (tide PL xi, figs. 17—19). The 

 stalks are colourless and very tough, and where a number of cells have been growing hide ly 

 side, they frequently coalesce at the base (PI. xi, fig. 21). 



The plant stands nearest to Sormotila mucigena Borzi (Studi Algologici, i, Messina 1883), but 



is distinguished by the much firmer integuments, which are never gelatinous, and by the larger 



size and greater irregularity of the cells. The cell-walls are also very much thicker end more 

 evidently lamellose. The disposition of cells and their aggregation into colonies is also quite 

 different. Moreover, Urococcus tropicus is aquatic in habit, whereas Ilormtila mucigena Borzi occurs 



on wet rocks. 



Zoogonidangia were not observed. 



The chloroplast is large and very granular, almost entirely filling the interior of the cell, and 

 it contains one pyrenoid (or rarely two). None of the cells contained the red-brown pigment 

 which is so characteristic of the other species of this genus. 



Family: EYDK0DI0T7ACE£ 



Genus : Pediastrum Meyen. 



t 



176. Pediastbum Teteas (Ehrenb.) Ralfc in Ann. Mag. Nat. Hist, xiv, 1884 



p. 469, t. 12, f. 4 

 Micrasterias Tetras Ehrenb 



iM.-Mansang, near Hsipaw (No. 24193) Between Tbingan-nyi-naung and 



Kawkareik. in tbe side-channel of a stream (No. 24483) 



177. Pediastrom 



Boktanum Menegh. Synops. Desm., 1840, p. 210 ; Ralf, Brit 



Desm., 1848, p. 187, t. 31, f. 9a. 



Sab— Mansang, near Hsipaw (No. 24193) 



All the specimens observed were very rough. 





