THE FRESHWATER ALG.E OF MADAGASCAR. 71 



angulis superioribas rotimdatis, apicibus truiicatis; a vertice visjc subcirculares ; 

 membrana irregulariter punctata ; pyrenoidibus singulis. 

 Long. 29-31 fi ; lat. 20-21 ^ ; lat. isthni. G-7 /i. 

 No. 1. 



The nearest species to this is Cosmarium contractum, Kirchn., from wliich it differs 

 in the form of its semicells with truncate apices ; the sinus is also more open, and the 

 vertical view is very different. 



117. Cosmarium zonaiuum, nov. sp. (PL VIII. fig. 13.) C. mediocre, circiier IJ-plo 

 longius qviam latum, leviter constrictum ; semicellula? semiellipticrc, in hasi angusti- 

 ores, apicibus levissime retusis ; a vertice visae circulares ; membranA, scrobiculatA, 

 sed zona glabra trans isthmum. 



Long. 72-76 ^ ; lat. 46-49 ^ ; lat. isthm. 44 ^. 



No. 0. 



The scrobiculations appear to have zones round them which refract the liglit differently 

 to the rest of the membrane (fig. 13, e). This species is nearest to Penmm australe, Racib. 

 (Desmid. w pod. naokol. ziem. p. 7, tab. i. fig. 11), but it is more constricted and is of 

 a different form, with more truncate apices, which are slightly refuse ; the membrane is 

 also sparsely scrobiculate and not irregularly punctate. 



118. Cosmarium pseudoconnatum, Nordst. Desm. Brasil. tab. iii. lig. 17. 

 Long. 50 n ; lat. 38 /u. 



No. 0. 



119. Cosmaeium viride, Josh, in Journ. Bot., Feb. 1885, tab. 254. fig. 3. (ColpopeUa 

 viridis, Corda, Almanach de Carlsbad, 1835, p. 206, tab. 2. fig. 28. Cosmarium 

 Cordanum, Breb. ex Rabenh Fl. Europ. Alg. iii. p. 177 ; C. Colpopelta, Breb. in 

 Pritch. Infus. ed. 1861, p. 734. 



Long. 47-48 ^ ; lat. 25-5-27 i« ; lat. isthm. 22-23 n. (PL IX. fig. 27.) 

 No. 1. 



120. Cosmarium coxicuM, nov. sp. (PL VIII. fig. 12.) C. par vum, circiter duplo longius 

 quam latum, leviter constrictum ; semicellulae truncato-conicae, apicibus rotundatis, 

 lateribus snbrectis, angulis basalibus rotundatis ; a vertice visae circulares ; membrana 

 punctata, seriebus transversis 2 vel 3 prope basin, ceteris irregulariter ordinatis; 

 pyrenoidibus singulis. 



Long. 37-42-5 ^i ; lat. 19-23 ^ ; lat. isthm. 18-21 a*- 



No. 0. 



This comes nearest to C. CucurUta, Breb., and C. PulangnUi, Breb., but differs from 

 them both in the form of its semicells, in its constriction and in its differently punctate 

 membrane. 



