158 BRITISH DESMIDIE^. 



5. D. Baculum (Breb.) ; segments very slender, having a solitary and 

 conspicuous inflation at the base, otherwise linear ; vesicles in a 

 single series. 



Closterium Baculum, Brebisson, AJg. Fed. p. 59. t. 8 (1835). 



Closterium trabeculoides, Corda, Observ. Mia-oscop. sur les Animal, de 



Carlsbad, t. 6. f. 44 (1840). 

 Closterium Sceptrum, Kiitzing, Phycologia Germanica, p. 133 (1845). 

 Docidium Baculum, Brebisson, in lit. cum icone (1846). 



Common. Carvarvon ; Dolgelley ; near Lampeter ; Penzance, &c., J. R. 

 Ashdown Forest ; near Storrington, &c., Sussex, Mr. Jenner. Near Bristol, 

 3Ir. Thwaites and Mr. Broome. Aberdeenshire, Br. Dickie and Mr. P. Grant. 

 Ambleside, Mr. Sidebotham. Rochdale, Mr. Coates. 



Falaise, Brebisson. Carlsbad and Prague, Corda. United States, Bailey. 



Frond very slender, many times longer than broad, distinctly constricted at 

 the middle. Suture strongly marked, but having no projections at the mar- 

 gins. Segments with a solitary inflation at the base, otherwise linear, the 

 ends truncate and without tubercles. 



Docidium Baculum may be readily recognized, as it is more slender than 

 any of the preceding species, and its inflations are more developed. 



Length of frond yiy of an inch ; greatest breadth ywzT '■> breadth at in- 

 flation ^ g'gg ; breadth at end o^Vr- 



Tab. XXXIII. fig. 5. a, b. fronds with endochrome ; c. empty frond mag- 

 nified 400 times. 



6. Z). tmnutum ; frond slender, slightly constricted at the middle; 



segments linear, not inflated ; vesicles in a single series. 



Dolgelley, J. R. New Forest, Hants ; and Parham Old Park near Stor- 

 rington, Sussex, Mr. Jenner. 



Frond minute, smaller than those of any of the foregoing species, linear, 

 the constriction often scarcely perceptible ; segments four to six times longer 

 than broad, the ends truncate. 



The smaller size and uuinflated state of Docidium minutum distinguish it 

 from D. Baculum. 



Length of frond -^\^ of an inch ; greatest breadth Y3V2 • 



Tab. XXVI. fig. 5. a. frond with endochrome ; b. empty frond. 



7. D. ? asperum (Breb.) ; frond slender, cylindrical, rough with minute 

 scattered granules, neither constricted nor inflated at the middle ; 

 ends truncate and dilated. 



Docidium asperum, Brebisson, in lit. cum icone (184G). 



Kerris near Penzance, /. R. 



Falaise, Brebisson. 



Frond slender, twelve or more times longer than ])road, rough with scat- 

 tered minute points which are best seen at the margins. Endochrome irre- 

 gular. 1 have seen neither vesicles nor terminal globules. 



