BRITISH DESMIDIEJE. 97 



f. 6. (1844) ; Trans, of Bot. Soc. of Edinburgh, v. 2. p. 151, t. IG. 

 Jeimer, Flora of Tunhridye Wells, p. 196. Hassall, Brit. AUj. p. 305. 



Common. Weston Bogs near Southampton, and several stations in Sussex, 

 Mr. Jenner. Dolgelley ; Penzance, &c., J. R. Hanham near Bristol, with 

 sporangia, Mr. Thwaites. Yate near Bristol, Mr. Broome. Kerry, Mr. 

 Andrews. Near Manchester ; and near Ambleside, il/r. (S/^eSoMayM. Craig- 

 endanoch (alt. 1436 feet), Aberdeenshire, Dr. DicA/e. Hill of Fare (alt. 450 

 feet), and near Aberdeen, and in Banffshire, Mr. P. Grant. 



Falaise, Brebisson. 



Frond smaller than that of Cosmarium margaritiferum, twice as long as 

 broad, deeply constiicted at the middle, the constriction causing a linear notch 

 on each side. Segments compressed, flattened at the end and crenate at the 

 margin, the surface punctate and even. The end view is elliptic. 



The sporangia, which have been gathered abundantly at Bristol by Mr. 

 Thwaites, are orbicular and spinous. The spines, which are very short, and in 

 fact not longer than broad, are divided at the apex and swollen at the base. 



The depressed ends distinguish this species from the next. 



Length of frond -^\-^ of an inch ; breadth at constriction ^iVr 5 breadth 

 of segment -^\^ ; diameter of sporangium -g\-^ ; length of its tubercles xoVo • 



Tab. XV. fig. 7. a. mature frond ; b. empty frond ; c. sporangium. 



10. C. undulatum (Corda) ; frond deeply constricted at the middle; 

 segments semiorbicular, crenate at the margin; sporangia with 

 elongated spines. 



Cosmarium undulatum, Corda, in Almanack de Carlsbad 1839, p. 243. t. 5. 

 f. 26. 



Near Ambleside, Mr. Sidebotham. Stapleton near Bristol, Mr. Thwaites. 

 Dolgelley, /. R. Henfield, &c., Sussex, Mr. Jenner. 



Carlsbad, Corda. 



Frond compressed, rather larger than that of Cosmarium crenatum, deeply 

 constricted at the middle, the constriction forming a linear notch on each 

 side. The segments are broader than long, crenate or undulate at the margin, 

 the ends rounded. The crenatures are caused by ridges, which are best seen 

 in an end view of the empty frond. The transverse view is elliptic. 



Mr. Thwaites has gathered the sporangia near Bristol. They are orbi- 

 cular, and their spines, which are divided at the apex and swollen at the base, 

 are elongated, and in this respect differ from the last species. 



It is not unlikely that some of the habitats given under Cosmai-ium crenatum 

 may belong to this species, since I had confounded these plants mitil Mr. 

 Thwaites' s discovery of the different sporangia. 



Length of frond ^i^ of an inch ; breadth of segment -g-^ ; diameter of 

 sporangium -j^-^ ; length of the spines of the sporangium g^^Vr- 



Tab. XV. fig. 8. a, b, d. front views; c. empty frond ; e. transverse view ; 

 f. sporangium. 



