BRniSIl DESMIDIE.E. l47 



tiients with which it is connected. In this separate state 1 can discover no 

 character by which to distinguish the sporangium of Tetmemonis from one 

 belonging to a species of Stattrocarpiis. 



This plant is in size intermediate between Tetmemorus Bi'ebissonii and T. 

 gramdatus. In figure it agrees with the former ; like the latter it has a hya- 

 line lip, but one far less conspicuous. This character induced me, in my paper 

 read before the Botanical Society of Edinburgh, to refer its sporangia to that 

 species, and I did not discover my error imtil I had seen the true sporangia of 

 T. granulatus. 



Tetmemorus Icevis is distinguished from T. Brebissonii either by the absence 

 of puncta or by their scattered state when visible ; its fronds also taper more 

 in the front Anew. From T. granulatus it differs in being more constricted at 

 the middle, and in havmg the front and lateral views dissimilar, irrespective of 

 the terminal notch. 



Length of frond from -^^ to -^^-^ of an inch ; breadth from yyxj ^^ ToTs > 

 breadth at constriction from ytjt to ttjt 5 length of side of quadrate sporan- 

 gium ,i^. 



Tab. XXIV. fig. 3. a. front view; b. side view; c. empty frond; d, e,f. 

 different stages of sporangium ; g. side view of sporangium. 



3. T. granulatus (Breb.) ; frond fusiform both in the front and lateral 

 views, and ending in a colourless projecting lip-like process. 



Closterium granulatum, Brebisson, Menegh. Sgn. Desmid. in Linncsa 1840, 

 p. 236. Kiitzing, Phy. Germ. p. 132. 



Tetmemorus gramdatus, Ralfs, Annals of Nat. Hist. v. 14. t. 8. f. 2 (1844) ; 

 Trans, of Bot. Soc. of Edinburgh, p. 134. t. 12. Jenner, Fl. of Tim- 

 bridge Wells, p. 198. Hassall, Br. Freshwater Algce, p. 378. 



Carnarvon; Dolgelley; Tal Sam near Lampeter, and Penzance, J.B. Sussex, 

 Surrey, Kent and Hampshire, 3/r. Jenner. Kerry, Mr. Andrews. Hanham 

 near Bristol, Mr. Thwaites. Charlton Fields, Manchester ; and Ambleside, 

 Westmoreland, Mr. Sidebothatn. Aberdeenshire (alt. IGOO to 2455 feet). Dr. 

 Dickie. Aberdeenshire and Banffshire (alt. 50 to 1600 feet), Mr. F. Grant. 



Falaise, Brebisson. Germany, Kiitzing. 



Frond fusiform, about six times as long as broad, and very slightly con- 

 stricted at the middle. The extremities always have a colourless projecting 

 lip-like process, which extends beyond the notch. The colouring is dark 

 green, and a few large vesicles are arranged in a longitudinal row down the 

 middle. 



The empty frond is minutely punctated ; the puncta generally form one or 

 two transverse lines in each segment near the central constriction ; in the other 

 parts of the frond they are not in rows, but scattered. 



Under a low power of the microscope this species much resembles the pre- 

 ceding ; but it may always be distinguished by the front and lateral views 

 being similar, and only differing in the terminal notch, which is not seen in 

 the lateral view. There is also beyond the notch a remarkable lip-like pro- 



