210 



FRESH-WATER ALG.E FROM BURMA 



basalibus late rotundatis et apice subtruncato, margine lateral! unoquoque spinis minutis 

 5-7 (plcrumque) prsedito, spinis ad angulos basales saBpe subirregulanter disposes et 

 numerosioribus ; a vertice visa3 elliptic*, spinis minutis 2-3 ad polos et seriebus leviter 

 divergentibus duobus spinorum intra polum unumqnemque ; a latere visa? subsph*erica3, 

 spinis minutis 2 ad apicem; membrana delicatissime scrobiculata et minutissime 

 punctulata inter scrobiculos, cum zona scrobiculorum prominentiorum in seriebus sub- 

 irregularibus 2-3 trans basin semicellularum juxta isthmum. 



Long, sine spin. 51/*; cum spin. 53'8/*; lat. sine spin. 42/*, cum spin. 46-5a*; 

 lat. isthm. 23/*; crass. 32/*. 



Bab. — Rangoon. (Joshua). 



Joshua's description of " Cosmarium spinosum" is very incomplete, and his figure is inexact. 

 He figures a single row of prominent scrobiculations across the base of each semicell, but his 

 specimens show a zone of these scrobiculations composed of two or three rather irregular rows. 

 The number of pairs of lateral spines is commonly five or six, but near the basal angles of the 

 semicells there are often one or two additional ones. 



There is little doubt that Xanthidium pidchrum Turn. (Freshw. Alg. E. India, 1893, p. 102, 

 t. 13, f. 10) is merely a form of X. spinosum. The semicells are of the same shape, the 

 *inus and the isthmus are precisely similar, and he also figures one of the rows of larger 

 8<Tobiculaticns across the base of the semicells. The additional epines at the basal angles are 

 sometimes met with in the Burmese species. Turner's vertical view (f, 10 b) is obviously inaccurate. 



We are inclined to think that X brevicorne Turn, is also a form of X spinosum, Turner 

 having failed to find the surface markings. X. eximium Turn, should also be enquired into with a 

 view to its relationship with X spinosum. 



Forma membrana scrobiculata in parte centrali semicellularum et meuibrana tota 

 minutissima punctata, 



Long, sine spin. 48-49/*. cum spin. 50-51/*; lat. sine spin. 39-43/*, cum 

 spin. 42-48-5/*; lat. isthm. 20*5-23/*; crass. 31/*. (Pi. xv, figs. 2, 3). 



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



118. Xanthidium Burkillii sp. n. (Fl. xv, fig. 10). 



X. submediocre, tarn longum quam latum (sine spinis), profunde constrictum, sinu 

 angusto extremo ampliato et extrorsum aperto ; semieellulse irregulariter subhexagonse, 

 parte inferiori ventricosa, angulis basalibus rotundatis, angulis lateralibus et apicalibus 



et spina elongata recta instructis, parte superiori laterum concavis, apice 



mam 



subrecto ; a vertice visae subellipticse , polis bimamillatis, mamillis binis poli uniuscujusque 



cum spiois divergentibus instructis ; in centro semicellularum leviter incrassato et eerie 



scrobiculorum 4 juxta et supra isthmum ; angulis mamillatis semicellularum subirregulariter 

 dispositis. 



Long, sine spin. Ufi, cum spin. 73-77/*; lat. sine spin. 44-45/*, cum spin. 

 77-81/t; lat. isthm. 16*5/*; crass. 24/*; long, spin, 18*5-20/*. 



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



This species possesses the same number of spines as X. antilopmum (Breb.) Kiits., but they 



axe more irregularly disposed, rather longer, and each one is attached at the apex of a 



projection. r 



; 



m 



