STAURASTRUM. 129 



recorded this variety from Yorkshire, N. Wales, the Shet- 



t/ 



lands, and from the west of Ireland, but we have since found 

 that the specimens in all instances were of the typical 

 form. 



Var. cristatum Liitkem. (PL CXVIII, fig. 14.) 



St. pileolatum Breb. var. cristatum Liitkem. Desm. Attersees, 1893, p. 566, 

 t, 9, f. 16; Gutw. Flor. Alg-. Mont. Tatr. 1909, p. 474. 



St. Leu-isianum Turn. Desm. Notes, Nov. 1893, p. 345, fig. 8 on p. 344 

 [figure incorrect" . 



\Vitli the basal arc of granules on the underside of 

 each apical angle transformed into small, longitudinally 

 compressed, emarginate verrucas. 



Length 35'5 lljn; breadth of base of semicell 

 20-22 //,, of apex 20-23 p. ; breadth of isthmus 15-16 p.. 



WALES.- -On the Llanberis slopes of Snowdon, 

 Carnarvonshire ! (J. H. Lewis). 



Geogr. Distribution.- -Austria and Galicia. 



The only important distinction between this variety and 

 the type is the duplication of the granules forming the lower- 

 most series on the underside of the apical angles. These 

 binate granules are situated on very small compressed warts, 

 which form arcs round the bases of the apical angles. 

 Liitkemuller found in his Austrian specimens a large granule 

 immediately under the point of junction of two adjacent arcs, 

 but we have not observed these granules in the Welsh speci- 

 mens. 



We have examined a number of the specimens collected by 

 Mr. J. H. Lewis on the slopes of Snowdon towards Llanberis 

 and have given an illustration of one of them (PL CXVIII, 

 fig. 14). These specimens were made the foundation of a 

 distinct species by Turner, under the name of St. Lewisianum, 

 but Turner's description and figure are both very inaccurate. 



4. Staurastrum rhabdophorum Nor cist. 

 (PL CXVIII, fig. 15.) 



Staurastrum rhabdophorum Nordst. Desm. Arctoae, 18*75, p. 36, t. 8, f. 40; 

 Wille, Ferskv. Alg. Nov. Semlj. 1879, p. 54 ; De Toni, Syll. Alg. 1889^ 

 p. 1179 j Roy & Biss. Scott. Desm. 1893, p. 242 (sep. p. 24). 



Cells rather under medium size, cylindrical, 1^-- 

 times as long as broad, very slightly constricted, sinus 

 a small notch, dilated inwardly ; semicells subquadrate, 



VOL. iv. 9 



