Mr. HassalFs Notices of British Freshwater Algce, 185 



a deep purple. It is distinguished from >S^^. glutinosus by the form 

 of the sporangium, size and colour of the filaments *. 



St. virescens. For description see * Annals and Magazine of 

 Natural History/ vol. xi. ; and for figure, PI. VII. and fig. 3. 



Synonym, Mougeotia quadrangulata, * Annals and Magazine of 

 Natural History/ vol. xi. 



This is readily distinguished from the two preceding species by 

 its much smaller size. 



St. . Filaments usually of a green colour and smaller 



diameter than those of St. affinis ; cells before conjugation 

 about eight or ten times as long as broad, but after that period 

 becoming much longer ; sporangium cruciform. PL VII. fig. 4. 

 Hab. Pond near Roydon, Essex. 



This species comes very near to St. virescens, from which it is 

 distinguished by its somewhat finer filaments and cruciform spo- 

 rangium, the sporangium in ;S^/. virescens being square. 



St. gracilis. Filaments of finer diameter than those of St. affinis, 



and usually of a green colour ; cells many times longer than 



broad; sporangia cruciform. See fig. 5. 



Hah. Penzance, Mr. Ralfs ; Rackham Bogs, Broadwater Forest, 

 Fishers Castle, Parham Park, Mr. Jenner ; High Beech, Hertford 

 Heath, Wormly West End, and Wanstead Flats, Essex. 



This is an abundant species, and very distinct from any of the 

 others. It was found by Mr. Ralfs, Mr. Jenner and myself, within 

 a few days of each other. 



St. gracillimus. Filaments more slender than those of St. gracilis, 

 and usually of a green colour ; cells very many times as long- 

 as broad ; sporangia cruciform, and about one-half the size of 

 St. gracilis. See fig. 6. 



Hab. Hertford Heath and High Beech, A. H.; Rackham Bogs 

 and Parham Park, Mr. Jenner. 



This species I have myself met with several times, but did not 

 at first recognise its distinctness, of which however I now enter- 

 tain no doubt ; and it was only on the receipt of a beautiful sketch 

 from Mr. Jenner, accompanied by remarks, that I examined 

 thoroughly into the matter and satisfied myself of its entire di- 

 stinctness. 



Nov. gen. Sph^rocarpus. 

 Cells filled at first with endochrome, which subsequently contracts 

 and assumes an irregularly spiral form; sporangia circular, 

 lodged in the transverse tubes. 



* I have since ascertained that this species was Jirst described in the 

 * English Botany.' I have, however, retained Agardh's name for it, the 

 term ccBrulescens being rarely, if ever, applicable to it, and therefore likely 

 to mislead. 



Ann, ^ Mag. N. Hist, Volisii. 



