Mr. HassalPs Notices of British Freshwater Conferva. 43 



Tyndaridea quadriformis. Filaments more slender than those 

 of T. interposita ; cells rather better than four times as 

 long as broad ; endochrome divided into two quadriform 

 masses. 



The cells are longer than those of T. interposita. 

 In ponds near Notting Hill. 



Tyndaridea interposita. Filaments of less diameter than those 

 of Tyndaridea bicornis ; cells usually three or three and a 

 half times as long as broad ; spores circular, lodged within 

 the cells ; endochrome somewhat quadriform. 

 Tyndaridea interposita is to be distinguished on the one 

 side from Tyndaridea quadriformis by the greater diameter 

 of its filaments, but somewhat shorter cells ; and from Tynda- 

 ridea bicornis on the other, in having longer cells, but some- 

 what finer filaments. 



Tyndaridea bicornis. Filaments of more considerable diameter 

 than those of T. quadriformis; cells usually better than 

 twice as long as broad, but sometimes longer and sometimes 

 shorter than this ; endochrome consisting of two distinct 

 masses united to each other by a lengthened tube of com- 

 munication, and emitting a kind of ray or prolongation from 

 each angle of their distal extremities : spores circular con- 

 tained within the cells. 



I have a suspicion that this is the species which is usually 

 taken for the Tyndaridea cruciata of Vaucher, which has how- 

 ever filaments of more considerable diameter and rather shorter 

 joints. It is by no means an uncommon species, but I have 

 only met with it in a state of conjugation in the Diana pond, 

 Bushey Park. 



Tyndaridea abbreviata. Filaments of rather greater diameter 

 than those of Tyndaridea stagnicola ; cells usually a little 

 longer than broad, but sometimes not so long ; endochrome 

 divided into two little masses, which, when magnified, re- 

 semble trees in miniature ; these are connected by means 

 of a transverse process, which may be compared to the 

 trunks of the trees : spores circular, contained within the 

 cells. 



This species approaches somewhat near to Tyndaridea stag- 

 nicola, from which, however, I am satisfied that it is distinct, 

 having had the opportunity of comparing the two species in 

 specimens in which the spores were perfect in both. From T. 

 stagnicola it is to be distinguished by the somewhat greater 

 diameter of the filaments, and by the shortness of the cells, 

 the spores appearing frequently to be in contact, so close are 



