18 ox THE DESMIDIE.E OF NORTH WAXiES. 



It has been found in two or three stations in North Wales, but not 

 elsewhere. The empty frond seems to be minutely punctate. 

 Co^7)mrium coronatum, nov. sp., (Plate V., Fig. 2.) 



Frond about as long as broad, or rather shorter ; constriction, deep, 

 linear ; segments, quadrilatei'al, narrowest at the base, and dilated 

 upwards, very slightly convex at ends, rough all over, with elongated 

 conical granules, arranged in lines, (about eight at the end and four on 

 each side ;) side view, truncate at the ends ; end view, elliptical. 



Length, -065 — -07 mm. ; breadth, -075 — -08 mm. ; isthmus, -02 

 mm. ; side view, "OiS mm. broad. 



This resembles Cos. hiretiim in form, but the granules are conical 

 and prominent, as in Cos. Brehissonii. The almost truncate ends, in 

 front view, have eight of these conical projections, which impart a 

 coronetted appearance. 



In side view the ends are also truncate, which would be sufficient 

 to distinguish it from closely allied species, and the regular elliptic 

 ends separate it distinctly from Cos. hiretum. By many features this 

 seems entitled to rank as a distinct species. 



Staurastrum anatinuni, nov. sp., (Plate V.. Fig .3.) 



Segments in front view, broadly fusiform ; rough with prominent 

 granules, which are truncate on the outer margin ; processes elongate, 

 rough, terminated With minute spines. End view tri-radiate, 

 processes elongate, rough, sUghtly and gradually concave, nodules at 

 the centre truncate. 



Length, -0.5 mm. ; breadth, including the processes, -1 mm. ; 

 breadth at the sinus, -02 mm. ; length of the processes, -025 mm. 



Allied to S. Sebaldi, but differs in the front view in the broadly 

 fusiform segments, and the upward rather than downward direction of 

 the processes ; hence the third process is usually visible on one or both 

 segments in the front view. 



Hence, if we denote new species by three asterisks, we may further 

 add to our list — 



***Cosmarium Cambricum. 

 ***Cosmarium coronatum. 

 *** Staurastrum anatinuni. 



Dr. Cooke has figured the following new or rare forms found by 

 myself at Capel Curig, in 1880, in recent numbers of " Grevillea," 

 viz.. Staiirastruin anatinum, S. aversum, S. Brasiliense, S. grande, S. 

 longisjnnuin, S. ophiura, Cosmarlum pseudoconnatum, Docidhun nodosum, 

 and the forms of Tetrachastrum representing T. oscitans, T. mucronatum, 

 and intermediate ones. 



I now add figvures of seven rare species not hitherto figured in 

 English woi-ks, all drawn from my own specimens, and to a uniform 

 amplification of 400 diameters, in addition to the three new species 

 described above. 



March loth, 1881, . A. W. Wills. 



