56 DR. С. $. WEST ON THE ALGÆ OF 
the misconceptions in the past have resulted from the failure to realise the 
differences which the apex presents when viewed from various positions. 
The second well-established form of Triploceras gracile is var. bidentatum, 
Nordst., in which the warts of the rings are bidentate. This well-known 
variety is frequent in Brazil, and has been found in India and New Zealand. 
The three following varieties are less well known ; they all occurred in the 
Yan Yean area of Victoria :— 
Var. ACULEATUM, JVordst. [T. gracile, subsp. aculeatum, Nordst. in Kongl. 
Sv. Vet.- Akad. Handl. xxii. no. 8 (1888), p. 64, t. 7. figs. 13, 14.] 
Forma aculeis verticillorum plus elongatis et patentibus ; verticillis 8-9 in 
semicellula unaquaque. 
Long. 238-260 ш; lat. bas. semicell. (sine acul.) 22 p, cum acul. 36-38 и; 
lat. apie. с. spin. 28-81 и. (РІ. 8. figs. 6-7.) 
Hab. Yan Yean Reservoir, at the weedy margins (Mar. 1905) ; also in 
pools in Ottelia Creek (Sept. 1907). 
The vertieillate warts of the semicells were aculeate, but the aculei were 
more spreading than in Nordstedt's New Zealand specimens, Playfair has 
described a forma australica of this variety from New South Wales, but the 
Victorian forms all possessed more spreading spines. 
Var. ROBUSTUM, var. п. (РІ. 3. figs. 4-5.) 
Var. major, elongatum et robustior, verticillis 16-18 in semicellula una- 
quaque, verrucis verticillorum mamillatis et spinatis ; processibus duobus ad 
apicem semicellularum elongatis et robustis, 2-4-aculeatis. 
Long. 560-584 р; lat. bas. semicell, c. spin. 43-45 u ; lat. max. apie. c. 
spin. 60 д. 
Hab. Yan Yean Reservoir, at the weedy margins (Jan. 1906); also in 
pools in Ottelia Creek and in Honeysuckle Flat (Sept. 1907). 
This large and handsome variety stands near to that described from New 
Zealand by Nordstedt as * var. bidentatum Ё. intermedia” (cf. Nordst. l. с. 
p. 64, t. 7. fig. 17). 
Var. DENTICULATUM, nob. [=?T. denticulatum, Playfair, in Proc. Linn. 
Sov. New South Wales, xxxii. part. i. (1907) p. 164, t. 2. fig. 11.] 
Var. verrucis verticillorum plerumque bispinatis (in parte apicali non- 
nunquam unispinatis), apice semicellulæ ut in var. aculeato verisimiliter. 
Long. 388—464 д; lat. bas. semicell. c. spin. 21:5-26 ш: lat. apic. semicell. 
с. spin. 19-27 р. (РІ. 3. figs. 8-10.) 
Hab. Yan Yean Reservoir, at the weedy margins (Mar. 1905). 
It does not seem possible to separate the form observed from Victoria 
from Playfair’s T. denticulatum, as the double rings of spines are charac- 
teristic of each form. In the Victorian specimens, however, some of the 
