THE PEESHWATEE ALGiE OP MADAGASCAE. 75, 



that of the typical form. One abnormal example (fig. 28, a') was noticed whicli had 

 the upper process on one side undeveloped. 



Forma beevior. (PL VIII. fig. 29.) Forma processibus brcviorihus et triundulatis 

 (utrobique). 

 Long, sine proc. 11-5 i.l, cum joroc. 31 /x; lat. cum proc. 29 /.; lat. IsHith. 5-5 ^. 



137. Staurasthum forcipatum, nov. sp. (PI. VIII. fig. 30.) S. parvum, paullo 

 longius quam latum (sine processibus), modice constrictum ; semicellula? hite cuneataj, 

 lateribus apicibusque leve subconvexis, angulis superioribus in processus longos 

 tenues glabros subcurvatos (leviter sigmatoideos) patentcs productis, apicibus uiii- 

 dentatis (ut visis) ; a vertice visa^ triangulares, lateribus subrectis, angulis in pro- 

 cessus longos tenues glabros curvatos (ut in *S'. cyrfoccro) productis, apicibus 

 forfi-culatis, dentibus magnis unguiculatis nodulo interjecto. 



Long. 135 /u ; lat. sine proc. 115 /u; cum proc. 385/*; lat. isthm. 4/i. 

 No. 1. 



This unique little Staurastrum is well characterized by its smooth arms with pincer- 

 like apices. 



138. Staurastrum gracillimum, nov. sp. (PI. VIII. fig. 31.) S. parvum, paullo longius 

 quam latum (sine processibus), profunde constrictum ; semiccUula) obsemicircularcs 

 apicibus subconvexis, angulis superioribus in processus divergentes gracillimos 

 undulates attenuates longos productis, apicibus profunde bifurcatis ; a vertice visae 

 triangulares, lateribus subconvexis, angulis in processus gracillimos undulatos 

 productis ; membrana glabra. 



Long, sine proc. 13*5 /u, cum proc. 42 fi ; lat. sine proc. 11*5 n, cum proc. 46 ^ ; lat. isthm. 

 4 /i. 



No. 36. 



This is much smaller and more delicate than ^S'. paradoxiwi, Meyen, var. longipes, 

 Nordst. (Bidrag till kiinn. sydlig. Norges Desm. p. 35, t. i. f. 17) ; its processes also 

 have only bifurcate apices. 



Var. BiRADiATUM, n. var. (PI. VIII. fig. 32.) Var. semicellulis latioribus; a vertice 

 visis anguste f usiformibus, processibus rectis. 



Long, sine proc. 10 yu, cum proc. 38 ^ ; lat. sine proc. 11'5 ^, cum proc. 50 w ; lat. isthm. 

 5/t ; crass. 3*8 /u. 



No. 36. 



139. Staurastrum hexacerum, Wittr. Om Gotl. och Oland Sottvat. Alg. p. 51. 

 {S. tricorne, Menegh. in Linnaea, 1840, p. 225.) 

 Forma trigona. 

 Long. 175 )u; lat. 23 /u; lat. isthm. 5'5/i. 



No. 0. 



l2 



