62 



with subtruncate ends, each semicell having a centrai protuberance. 

 Dim. 36 « 22 « ó 7. 



Cosmariuiìi gotlandicum Wittr. v. cambrense n. v. p. 845, f. 7. 

 Fairly similar to the type, except that it is proportionally much nar- 

 rower. Dim. 35 » 22 « ó y. 



Sianrastrum lewìsianum n. s. p, 346, f. 8. Related to S capi- 

 tulum Bréb. and S amoenum Hilse It differs from the former 

 in being doubly sinuate at the sides. and from the latter in having 

 two rows of verrucas. hi this form the lower verrucee are piain, the 

 upper series being minutely dentate or serrate. In vertical view the 

 sides are gently incaved, the apices (3-4) being rounded. Dim. 37-42 

 '^ 18-21 « i3-ió 7. 



S. weslii n. s. p. 346, f. 9. Seemingly between S. Griffithsia- 

 num Naeg. and S. diplacanthum De Not. Each angle possesses 

 3 or 4 spines at the upper margin, with 5 short, toothed, thick pro- 

 cesses, arranged in quincunx. Dim. e. sp. 28-32 « 23-2Ò a,; s. sp. 

 25-28 « 18-21 « 8-10 [}., 



S. dìplacaiilìiuni v. anglicum n. v, p. 3-(5, f. io. Differs from the 

 Italian type of De Notaris in having the apices more convex, and 

 crowned with little verrucse; it has a number of aculei wanting in 

 the type. Dim. e. sp. 37-41 ^ 34 y.; s. sp. 27-32 « 28 «9-11 y. 



S. eboracense n. s. p. 345, f. 11. Small, with 4 incurved arms, 

 rounded at the ends; each arm with 3 or 4 rows of conical granu- 

 les; sides sinuate; sinus rounded. It has an apical corona of little 

 verrucae: remainder, except arms, smoth. Dim. 25 « 27 « 7 a. 



S. treìlcckense n. s. p. 345, f. 12. Small, semicells ovai, covered 

 with a few rows of short stout aculei; each spine very dilate at base; 

 angles rounded, each with 6 or 7 short plain aculei. Sinus narrow. 

 Dim. e. sp. 33^32 y.; s. sp. 3o ^^ 28 » 14 y.. 



Micrasterias papììlifera v. varvicensis n. v. p. 345, f. i3. The side 

 lobes and lobules incised almost as in M. Gru x-meli ten sis 

 Ehrenb. 



Peniiim Leiuìsìì n. s. p. 346, f. i5. A near congener of P. cylin- 

 drus (Ehrenb.) Bréb., but differs in its fine granulations, its dilated 

 ends, and its colourless membr. Long, and lat. 46,11 and 62. i y.. 



Nach W. und G. S. West («Some recently published Desmidiea}» 

 in Journ. of Bot., 1895, p. 2) ist diese Art nur cine grosse Form 

 von P. exiguum West Freshw. alg. of \V. Ireland p. 126, pi. XIX, 

 figg, 17, 18, wesshalb die Verff. sic P. exiguum West f. Lewisii 

 nennen. 



