THE FEESH WATER ALG.E OF AlADAGASCAK. 



r).) 



ampliato; seniicelhilge truncato-pyramidatse, angiilis infcrioribus late rot\mdatis 

 levissime triundulatis (rel angularibus parte infiiiia sul)diveri,^(Milil)us) ot iiicrassatis 

 lateribus apicem versus valde retusis, apicibus truncjitis levissime triundulatis, 

 angulis superioribus incrassatis subrotuudatis ; a vorticc visae elliptical polis 

 angularibiis angulis tribus obtusis, medio utrobique suljinflatae ; a latere visse 

 truncato-ovatse, angulis superioribus et iuferioribus incrassatis ; membnmA, minute 

 punctata; pyrenoidibus singulis. 

 Long. 25-33 ^ ; lat. 20-25 ^i ; lat. istlim. 5-7'6 ; crass. 11-13'5 /«. 

 iNTos. 0, 1, and 10. 



This species was seen in abundance, and is nearest to Cosniarinm trilohnlatum, Keinsch 

 (Algenfl. mittler. Theil. von Franken, p. 116, taf. ix. fig. vi), from which it differs in 

 its subundulate and incrassated sides and apex, in its punctate membrane, and in the 

 subtumid and angular vertical view, as well as in its semicells being distinctly less 

 trilobed. Compare also with C. eductum, Roy et Biss. in Nordst. Desmidieer Mn 

 Bornholm, p. 198, tab. vi. fig. 8. 



Forma minor. (PI. VI. fig. 30.) 



Long. 21 fjL ; lat. 15 n ; lat, isthm. 45 n ; crass. 9*5 ^, 

 No. 1. 



59. CosMAUiTJM suBAimicuLATUM, nov. sp. (PL VL fig. 31.) C, mediocre, tarn longum 

 quam latum, modice constrictura, sinu aperto ad extremum subampliato ; semicellulae 

 subelliptic^e, dorso convexiore, supra latus unumquodque spinis tribus brevibus 

 obsessa? ; a vertice visse late elliptica?, ad polum unumquemque cum spin{\ singubi 

 brevi ornatse ; a latere visa? depresso-spha3ric8e ; membrana irregulariter punctata ; 

 pyrenoidibus binis. 

 Long. 43-46 ^ ; lat. sine spin. 43-44 /u ; lat. cum spin. 44-48 yu ; lat. isthm. 21-25 ^ ; 



crass. 28 n. 



No. 1. 



This is near C. auriculatmn, Keinsch (Contrib. Alg. et Fung. t. xiv. fig. 5), but the 

 sides are not produced into a tridentate process, the sinus is open, the membrane is not 

 granulate, and the vertical view is broader and not produced at the poles. Compare also 

 with a erosiim, Delp., and C. laticollum, Delp, 



60. CosMAEiuM LuNDELLii, Belp. Spccim. Desm. Subalp. p. 109, t. 70. fig. 62-6i. 



Var. MADAGASCAiiiENSE, nov. var. (PI. VIII. fig. 2.) Var. septim^ parte longior quam 

 lata, semicellulis in centre non incrassatis, a vertice visis elUpticis, polis latissime 



rotundatis. 

 Long. 81 /i ; lat. 70 ^t; lat. isthm. 33 a^; crass. 43 ^. 

 Nos. and 18. 



