WELWITSCH's AFRICAN FRESHWATKR ALG^. 37 



IX. — Temnooametace^. 



Ordo novus Conjuoatarum, conjugatio solum inter cellulis 



speciatim abstrictas. 



1. Temnogametum, gen. n. 



Cellulfe vegetativae ut in Mougeotia, cylindricse, chromatophoro 

 elongate complanato pyrenoidibus uniseriatim dispositis ; propagatio 

 zygosporis conjugatione scalariformi lateralive cellularum brevium 

 specialium abstrictarum formatis. 



1. T. heterosporum, sp. unica. T. cellulis vegetativisdiametro 

 6-12-plo lougioribus, cbromatophoris pyi-enoidibus parvis globosis 

 1-6 (plerumque 5) ; cellulis conjugantibus diametro l|^-2i-plo 

 longioribus ; zygosporis ubi conjugatione scalariformi productis 

 paene x -formibus, robustis cum angulis truncatis, ubi conjugatione 

 laterali oblique subcylindricis, latere altero recto concavove, altero 

 convexo, polis truncatis. Crass, cell, veget. 14-5-17 z^; lat. zygosp. 

 conj. seal. form. 48-59 //, long. 39-50 /x; lat. zygosp. couj. later. 

 form. 20-26 /x, long. 61-67 /x. 



Huilla. Forming dense intricate masses with Gonatonema 

 tropicnm, Zijgncma apontaneum, and StUjeoclonium? sp., Morro de 

 Lopollo ; Febr. 1860. No. 172. 



This is a remarkable plant more particularly on account of its 

 special conjugating cells ; these are short, and cut off either singly 

 or in pairs at intervals along the filaments. In the former case the 

 conjugation is scalariform ; these special cells in two contiguous 

 filaments put out short rounded conjugating tubes which unite, 

 the cells themselves becoming bent towards each other, and very 

 soon the two cells coalesce and form the zygospore. In this way a 

 zygospore is produced which at first sight very much resembles the 

 central cell of the five cells constituting the spore of a Mougeotia 

 of the section Staurospermece. In those filaments in which the 

 pairs of cells are cut off the conjugation is lateral, the two cells 

 forming a zygospore much resembling the aplanospore of a Gonato- 

 nema. In fact, these zygospores are oblique, and the convexities 

 and concavities alternate along the filament precisely as in the case 

 of a sporiferous filament of the latter genus. 



Both scalariform and lateral conjugation occur in the same 

 filaments. In all the specimens observed (which had been dry for a 

 long period) the contents of the thick-walled spores appeared to 

 have contracted into two approximate rounded masses ; whether 

 the latter had ever been perfectly united or had yet to unite within 

 the wall of the spore is a matter that could not be definitely decided 

 from the material. 



On account of the peculiar conjugation, this plant must be 

 placed as the type of a new order — iemnngametacea — of Cunjiigatce. 



X. ZYGNEMACEiE. 



. 1. Mougeotia Ag. (1824); em. Wittr. (1878). 

 1. M. (§ Staukospermum) uberosperma, sp. n. M. cellulis 

 vegetativis diametro 4-8-plo longioribus, cellulis conjugatis genu- 

 flexis ; zygosporis maturis angulari-globosis (cum angulis 5-6), 



