mmm 



THE FRESHWATEK ALG.^ OF MADAGASCAR. 67 



superiore, 3 in seric mediana, 4 in serie inferiore, gianulo suj^ra istlimiira nullo; a 

 yertice visis polis eniarginatis, lateribus medio utrobiquc -ranulis tril)us, granulis 

 quattuor intra marginem iustructis. 



Long. 39 /I ; lat. 38 ju; lat. isthm. 15 /^ ; crass. 21 /i. 



No. 0. 



This variety is very similar to Cosmarlmn taxwhondnim, Lund., var. hUentulum, 

 Lagerli. (Bidrag till Amerikas Desmidie-riora, p. 237, tah. xxviii. fig. 8), but has tlic 

 central granules diflPerently arranged, is without the large sharp granule above tlic 

 isthmus, and also has two undulations above the subtruncately toothed basal angles. 



Var. SUBUNDTJLATUM, Boldt, Siber. Chlorophylloph. p. 101, taf. v. fig. 4. 



Torma subdenticulatum. (PL VII. fig. 4.) Forma lateribus subdenticulatis (non uii- 

 dulatis), granule supra isthmum nullo ; a vertice visa polis triundulatis. 

 Long. 26-27 ju ; lat. 24-25'5 ^t ; lat. apic. 14-5-16/u ; lat. isthm. 6-7-5^; crass. 15 /i. 

 No. 1. 



Var. DENTATUM, nov. var. (PI. VII. fig. 5.) Var. minor et paullo latior quam longa ; 

 semicellulis subangularibus, apicibus late truncatis, angulis superioribus inferiori- 

 busque dente instructis, lateribus tridenticulatis, serie dentium 4 intra apicem, 

 serie granulorum 3 in centro, et granulo singulo supra istlmium ; a vertice visis 

 polis triangulatis, in medio utrobique triangulatis, intra marginem dentibus 4 

 prseditis ; a latere visis subrotundis, apice subtruncato, angulis superioribus uniden- 

 tatis, lateribus granulis duobus obsessis. 

 Long. 27 /< ; lat. 31*5 ^i ; lat. apic. 20 /i; lat. isthm. 9o ^ ; crass. 19^. 

 No. 0. 



On comparing the var. dentatum w itlj the typical C. taxichondrum they hardly seem 

 to belong to the same species, but var. siibundulatum, with its forma suhdenticidatum, 

 certainly connect the two. 



Var. COMPRESSUM, nov. var. (PI. VII. tig. 6.) Var. IJ-plo latior quam longa, semi- 

 cellulse subangulares, apicibus subtruncatis, angulis inferioribus rectangularibus 

 prope basin ; in medio seriebus duabus granulorum apicem versus, 2 in serie 

 superiore, 3 in serie inferiore ; a vertice visse angustiores, polis bidentulatis, in 

 medio utrobique granulis tribus et duobus intra marginem instructac, mcmbran^ 

 dense sed minute jmnctata. 



Long. 31 /x; lat. 41^; lat. isthm. 14 /i; crass. 18 /x. 



No. 0. 



106. CosMAEiUM NOTOCHOXDBUM, nov. sp. (PL VII. fig. 1.) C. parvuui, li-plo latius 

 quam longum, profunde constrictum, sinu lineari ; scmicellulae rectangulares, angulis 

 inferioribus rectangularibus et apiculatis, angulis superioribus truncatis, in medio 

 latere unoquoque cum apiculo, apicibus levissime concavis, juxta apicem serie 



k2 



