/ 



ARTHRODEMU- 



211 



119. Xanthidium sexmamillatum sp. n. (PL xv, figs. 11, 12). 



X. submediocre, paullo longius quam latum (sine spinis), profundissime constrictum, 

 sinu late aperto et obtuso ; semicellulse transverse suboblongo-elliptica*, parte superiori 

 niarginum lateralum trimamillato, mamilla unaquaque spina perlonga recta pnedita 

 spinis inferioribus subhorizontaliter dispositis, spinis superioribus et medianis Kursum 

 divergentibus, projectione parvo infra mamillam inferioreoi utrobique, aj)ice concavo vtl 

 nonnunquam recto; a vertice visre ellipticae, polis leviter attenuatis et epina perlong* 

 prseditis, tumore minuto vel membrana incrassata ad medium utrobique. Merabraaa punc- 

 tata, in centro semicellularum leviter incrassata. 



Long, sine spin. 40-48-5/*, cum spin. 66-5-76/* ; lat. sine spin. 34*5-40/*, cum. 

 spin. 67-81^; lat. isthro. 7*5-9*5/*; crass. 18-23/*. 



Hab. — Mansang, near Hsipaw (No. 24193). In the Kan-gyi at Mudon (No. 24506 ). 



This species conies nearest to X. Bengalicum Turn., but is distinguished by its wi«Wy open 

 sinus and the form of the semicells. The six spines of each tMnioell nre situated on tiv tpioet 



of six mamillate projections, which are absent from X Bengalicum. The thickened area in (he centre 

 of the semicells is somewhat variable, and may be represented by an internal thickening of the 

 cell-wall, or by a very small, projecting tumour. 



Var. robustum — var. n. (PI. xv, fig. 13). 



Var. sinu minus aperto, spinis inferioribus et medianis utrobique brevioiibus 

 et validioribus, spinis superioribus minutis (multe reductis). 



Long, sine spin. 45/*, cum spin. 52-54/*; lat. sine spin. 46m, cum spin. 71/* 

 lat. istbm. 10/*; eras?. 27/*. 



^ a j. — Mansaug, near Hsipaw (No. 24193). 



Genus: Arthrodesmus Ehrenb. 



120. Arthrodesmus triangularis Lagerh. Bidr. Amerik. Desm.-fl. 1885, p. 244 



A. Incus (Breb.) Hass. var. triangularis Lagerh. in Nuova Notarisia, 



iv, 1893, p. 182. 

 Forma cellulis longioribus quam forma typica, dorso semicellularum elevation et 



minus retuso 



, , • • ifl iq (1 n„ m SD in. 43-16u; lat. isthm. 4*3-5*3/* 



Long. 20-24/*; lat. sine spin, lo-19/*, cum spiu. to P , 



(PI. xv, fig. 7). 



Hub.— Mansang, near Hsipaw (No. 24193). 



121. Arthrodesmus 



curvatus Turn. Freshw. Alg. E. India, 1893, p. 135, t. 11 



f. 31, 33; t. 12, f. 2, 7, 13 ; 15. 

 Var. Burmensis var. n. (PL xv, fig. 9). 

 Var. cellulis diametro circiter IJ-plo longioribu*, sinu plus aperto 



obsemicircularibus, apice valde convexo. 



OC( . n „ m srn ' n 87^; lat. isthm. 11*D> 



Long. 47/*; lat. sine spin. 36*0/*, cum spin, o//* , 

 JfrJ.— Mansam?, near Hsipaw (No. 21193). 



semicell 



• 



