THE FEESHWATER ALQM OF MADAGASCAR. 81 



156. Pediastrum duplex, Meyen, Beob. iiber Algenfl. p. 772. tab. 13, figs. 6-10, (^t 

 figs. 16-19. {Pediastrum pertusum, Kiitz. Pbycolog. Germ. p. 113; llabenh. PI. 

 Europ. Alg. iii. p. 75.) 



Var. CLATHRATrM, A. Br. Alg. Unicell. p. 93; Beinsch, Algcnfl. von Prank, pp. 93-94, 

 tab. X. fig. V. (PL IX. figs. 41, 42.) 

 Diam. coenob. 73-79 p. ; diam. cell, periph. 115-17 /jl. 

 Nos. 1, 3, and 18. 



Var. ASPERUM, A. Br. Alg. Unicell. p. 93. 

 No. 0. 



157. Pediastrum tetras, Ralfs, in Ann. Nat. Hist. vol. xiv. p. 409, tal). xii. fig. i; 

 Brit. Desmid. p. 182, t. xxxi. fig. 1. (Micrasterias tetras, Elircnb. Infusoria, p. 155, 

 n. 182, tab. xi. fig. 1.) 



Porma a. Dispositio cellulariim 4. (PL IX. fig. 40.) 

 Nos. 1 and 3. 



Porma h. Dispositio celhilarum 1 + 7. (PL IX. fig. 39.) 

 Nos. 0, 1, 18, and 22. 



158. Pediastrum enoplon, nov. sp. (PL V. figs. 1, 2.) P. coenobiis orbicularibus, 

 e cellulis 16-64 formatis consociatis; eellulis periphericis late oblongis (2i-3J-plo 

 latioribus quam longis) et curvatis, in medio exteriore cellula3 uniuscuj usque spina 

 longa valida attenuata ornatis, apice truncato-emarginatis ; cellulis centralibus 



riradiatis ad fines connexis, aperturis magnis inter eas ; membrana cellularuin 

 glabra vel cellulis vetustis punctata. 

 Diam. coenob. 98-160 f.i\ diam. cell, peripli. 115-26 ^u; long. spin. 19-27 /i ; crass. 

 spin, ad bas. 4-6 fx ; crass, spin, ad apic. 1-1 '8 ^. 

 No. 36. 



This characteristic species differs from all others in the form of its cells, in its long 

 single peripheral spines, and in the large apertures. 



Order SORASTEE^. 

 Genus Staurogenia, Kiitz. 



159. Staurogenia emarginata, nov. sp. (PL V. fig. 25, 20.) S. cellulis coenobii 2-4, 

 paullo longioribus quam latis, subhexagonis, angulis rotundatis, lateribus rctusis, 

 apicibus profunde emarginatis. Propagatio fit cellulis filialibus quatuor in ceUula 

 matricali ortis. 



Long. cell. 11-12 /u; lat. ceU. 12-5-14'5 /u. 

 No. 1. 



Genus Ccelastrum, Nag. 



160. Ccelastrum sph^ricum, Niig. (Ccelastrum Ndgelii, Eabenh. PL Europ. Alg. iii. 

 p. 79, pro parte.) 



No. 3. . 



SECOND SERIES.— ^BOTANY, VOL. V. ^ 



