126 BRITISH DESMIDIACE^E. 



This species lias so far only been observed from the west 

 of Cornwall and from the Shetland Islands. It may be a 

 western British type, but we have not succeeded in finding- 

 it either in the west of Ireland or in the Outer Hebrides. 



SPECIES TO BE ENQUIRED INTO. 



The four following* Cosmaria are only imperfectly known. 

 They were very briefly described by Archer, whose promised 

 detailed information concerning them never appeared. 



COSMAEIUM LASIOSPORUM Arch, in Quart. Journ. Micr. Sci. 

 xix, 1879, p. 123; Cooke, Brit. Desm. 1886, p. 92; De Toni, 

 Syll. Alg. 1889, p. 46. Ursinella lasiospora Kuntze, Revis. 

 gen. plant. 1891, p. 925. " Very minute (scarcely so large as 

 C. tinctum}. Sinus linear. Semicells flattened at the apex. 

 Zygospore globose, beset with extremely minute, fine, and 

 pointed spines." Size . . . . ? 



H cib.- -Ireland (in pools). 



COSMAEIUM LOBATOSPOfiUM Arch, in Quart. Journ. Micr. Sci. 

 vii, 1867, pp. 170-172; Kabeiih. Flor. Em-op. Alg. Ill, 1868, 

 p. 179; Cooke, Brit. Desm. 1887, p. 121; De Toiii, Syll. Alg. 

 1889, p. 1055. " Frond very minute, nearly twice as long as 

 broad, general form elliptic; ends rounded, constriction an 

 extremely shallow and very gentle narrowing. Zygospore 

 rounded, somewhat irregularly lobed ; lobes surmounted by 

 one or two minute, pellucid, conical, and pointed spines or 

 mucros ; cell-wall reddish. Length 15 /u ; breadth 10 /x ; diam. 

 zygosp. 25 ju." 



Hob.- -Ireland (in bog pools). 



COSMAEIUM MINUTISSIMUM Arch, in Quart. Journ. Micr. Sci. 

 xvii, 1877, pp. 194 and 301 ; Cooke, Brit, Desm. 1886, p. 91. 

 " Very minute, resembling Sphserozosma excavatum, but more 

 minute, and with the sinus a narrow incision. Zygospore 

 ellipsoidal or oblong, of a purplish or bronze-like hue, with 

 thick walls." Size . . . . ? 



Hob. Ireland . 



We observed a small Cosmariiim in Welwitsch/s collections 

 from Angola, W. Africa, which we doubtfully referred to 

 C. inlnutissimum Arch, (vide West & Gr. S. West, ' Welw. Afric. 

 Freshw. Alg/ 1897, p. 120). We described it as follows: 

 "Very minute, about 1J times longer than broad, deeply con- 

 stricted, sinus linear with a dilated extremity ; semicells 



/ t/ * 



elliptic-semicircular. Side view of semicell subcircular. 



