Fresh- water Alym of Canada. 343 



and less lubricous than in endiviafolio ; mature specimens, are 

 leathery to the touch. Its peculiar characteristic, in which it 

 differs from any other known to us, is the mamillce or wart-like 

 protuberances which cover its fronds. Tuberculosa would have 

 been a good descriptive name, but this has already been given 

 to another, and a very different species. We have therefore 

 ventured provisionally to call it mammosa. These protuberances 

 arise from the peculiar form of the contained filaments, the ramuli 

 of which are found to branch dichotomously, and ultimately to 

 form tuffs not unlike an umbel. Several of these tuffs grouping 

 together form external protuberances on the mucous. This species 

 is undoubtedly closely allied to the preceding, but is clearly more 

 than a mere variety. Its main branches are neither so delicate 

 nor so long as its are, and even to the eye the mamillse give it a 

 character peculiar to itself. 



III. Ch. TUBERCULOSA, HooJc. 



Char. — Gelatinous matrix, at first glabrous and firm. Filaments 

 very slender, fiexuous, hyaline. Bamuli coloured palmate 

 fasciculate. — Harvey. 

 HassalPs Hist. Brit. F. Algce. p. 126, Plate IX, figs. 7, 8 ; Harvey 



in Manual, 1st edition, p. 121. 

 Hob. — In a pool at the west end of St. Helen's Island, adhering 

 to the stems of aquatic plants, and to stones. 

 Harvey describes the fronds of the European species of this plant 

 as bright-green, and an inch and more in diameter. The largest of 

 our specimens have not exceeded a quarter of an inch, and several 

 of them are no larger than the head of a pin. In this respect they 

 bear a resemblance to C. elegans, which according to Vaucher " is 

 formed of gelatinous protruberances of all sorts of figures, and of 

 a diameter which varies from a point to an inch." It is evidently 

 identical with the Batrochospermum intricatum of Vaucher. In 

 English Botany the filaments are figured without ciliee, and in this 

 respect agree with our specimens. We have no doubt that this is 

 a permanent character and distinguishes it from C. elegans, whose 

 apices are seligerous and produced beyond the gelatine. Under 

 the microscope this is an exceedingly beautiful object. The cells 

 of the filaments are about one and a half times long as broad, and 

 in maturity become round and bead-like. The branches begin at 

 the fourth or fifth cell from the base of the filaments and bifurcate 

 at every fourth or fifth cell twice or thrice ; the ultimate ramuli 



