158 BRITISH DESMIDIACE^;. 



151. Staurastrum vestitum Kalfs. 

 (PI. CLI, figs. 9-11 ; PI. CLII, figs. 5, 6.) 



Staurastrum vestitum Ralfs, Brit. Desm. 1848, p. 142. t. 23, f. 1 ; Arch, in 



Pritch. Inf. 1861, p. 742 ; Rabenh. Krypt.-fl. Sachs. 1863, p. 193 ; Flor. 



Europ. Alg. 1868, p. 218 (in part) ; Jacobs. Desm. Danem. 1875, p. 207 ; 



Delp. Spec. Desm. subalp. 1877, p. 159, t. 12, f. 46-49 ; Kirchn. Alg. 



Schles. 1878, p. 167 ; Wolle, Desm. U. S. 1884, p. 138, t. 45, f. 28-30 ; 



Cooke, Brit. Desm. 1887, p. 175, t. 60, f. 3 ; De Toni, Syll. Alg. 1889, 



p. 1218 ; West, Alg. Engl. Lakes. 1892, p. 20 ; Roy & Biss. Scott. Desm. 



1893, p. 26 ; West & G. S. W T est, Alg. S. England, 1897, p. 496 ; Schmidle, 



Lappmark Siisswasseralgen, 1898, p. 63 ; G. S. West, Variation Desm. 



1899, pp. 374, 395; West & G. S. West, Alga-fl. Yorks. 1902, p. 106; 



Alg. N. Ireland, 1902, p. 54. 



Didymidium (Staurastrum) vestitum Reinsch, Alg. Frank. 1867, p. 167. 

 Staurastrum vestitum var. ornatum Istv. Diag. praev. Alg. nov. Hung. 



1887, p. 240. 



Cells of medium size, about 1^-2 times broader than 

 long, deeply constricted, sinus open ; semicells sub fusi- 

 form, lower margin ventricose, apex slightly convex with 

 about 6 emarginate granules, and two prominent emar- 

 ginate or bifurcate spines just under the apex ; angles 

 gradually produced to form fairly long processes, 

 usually nearly horizontal or slightly converging, tipped 

 with 3 strong spines and provided with several concen- 

 tric series of denticulations. Vertical view triangular, 

 angles produced into denticulate processes, lateral mar- 

 gins concave, with two prominent bifurcate spines 

 projecting from the middle of each, and sometimes with 

 smaller emarginate verrucse on each side ; with a dorsal 

 series of emarginate granules just within each lateral 

 margin. 



Zygospore globose, with numerous spines bifurcate 

 at the apex (Wolle). 



Length 28-43 (JL ; breadth, including - processes, 46- 

 90 pi ; breadth of isthmus, about 9 \i. 



ENGLAND. Near Bowness ! (Bissett), Deep Vale, 

 Loughrigg, and in the plankton of Easedale Tarn, West- 

 moreland ! Biccall Common, E. Yorks ! Hawkshead, 

 Lancashire ! Thursley Common, Surrey ! Near Pul- 

 borough, Sussex (Ralfs). New Forest, Hants ! Dart- 

 moor, Devon (Harris), St. Just, Cornwall ! 



WALES. Capel Curig ! (Cooke & Wills) and Llyn- 



