Nov. 1904. | BOTANICAL SOCIETY OF EDINBURGH. 23 
Var. septentrionale, Wille. O.—Hoy. S.—Lerwick. 
Var. cymatium, var. n. (fig. 19). 
Var. marginibus lateralibus semicellularum minute undulatis. 
Long. 24-27 ; lat. 17-18u; lat. isthm. 46-54. O.—Hoy. 
182. C. goniodes, W. and G. 8S. West, in “ Trans. Linn. Soc.,” bot. ser. 2, 
1895, p. 70, t. 8, f. 8. ; 
Var. variolatum, var. n. (fig. 18). 
Var. semicellulis brevioribus, levissime attenuatis, angulis 
superioribus subrotundatis, apicibus levissime retusis ; a latere 
visis ovato-pyramidatis ; a vertice visis late ellipticis ; membrana 
punctulata, punctulis delicatissimis et multe distantibus ; cellulis 
tere tortis. 
Long. 20-21°3u ; lat. 10°6-12°2u ; lat. isthm. 8°5-8°8y ; crass. 
85m. 
S.—Near Scalloway. 
This variety stands nearer to CU. gontodes, var. subturgidum, 
W.and G.S. West (in “ Trans. Roy. Irish Acad.,” xxxiii., sect. B, 
1902, p. 41, t. 2, f. 12), than to the typical form. It is dis- 
tinguished, however, by its shorter semi-cells, and its variolated 
cell-wall. 
1838. C. Cucurbita, Bréb. O—Kirkwall; Hoy. S.—Lerwick ; Scallo- 
way ; Neugles Water. 
184. C. annulatum (Nag), De Bary, var. elegans, Nordst. Long. 
57'5u ; lat. 25u. S.—Scalloway. 
Genus XANTHIDIUM, Ehrenb, 
185. X. antilopewm (Bréb.), Ktitz. S.—Neugles Water; Loch Brin- 
dister ; Bressay. 
Var. depauperatum, var. n. [X. antilopewm, forma, W. and 
G. S. West, “Scott. Freshw. Plankton I.,” “ Journ. Linn. Soc.,” 
bot. xxxv., 1903, p. 589, t. 16, f. 1.] 
Var. cellulis leviter inflatis, angulis lateralibus cellularum 
valde obtusis vel levissime trunecatis; spinis paucis (1-3 ad 
marginibus lateralibus semicellule unzequaque), brevioribus et 
tenuioribus, subirregulariter dispositis. 
Long. sine spin. 46-55-5u ; lat. sine spin. 43-50u ; long. spin. 
2-9-5; lat. isthm. 9°5-14u (figs. 15 and 16). 
S.—Plankton of Neugles Water, Loch Brindister, and of Loch 
Beosetter, Bressay. 
This variety differs from the type in the form of the semi-cells, 
and in the fewer, thinner, and irregularly disposed spines. The 
disposition and number of the spines is extremely variable, and 
is generally different on the two semi-cells of the same individual. 
It is such a constant feature of the Scottish plankton that we 
think it deserves a special varietal name. 
186. X. fascieulatum, Ehrenb. 0.—Kirkwall ; Hoy. 
187. X. concinnum, Arch. O.—Finstown. S.—Lerwick. 
Genus ARTHRODESMUS, Ehrenb. 
188, A. convergens, Ehrenb. 0.—Hoy. S.—Near Scalloway; near 
outlet. of Loch Beosetter, Bressay. 
189, A. Incus (Bréb.), Hass. O.—Kirkwall; Hoy. S.—Scalloway. 
Var. Ralfsiz, W. and G. S. West. O.—W. of Kirkwall. 
Var. intermedius, Wittr. S.—Near Lerwick. 
