Dublin Microscopical Club. 147 



of a siimy stiff calf s-foot jelly. Uuder the top surface there were 

 a series of what appeared like surfaces of growth that gave a vertical 

 section somewhat the appearance of some agates. 



November 20, 1884. 



Canadian Specimen of Cosmarimn notabile, Breb. — Mr. Archer 

 drew attention to specimens of Cosmarium notabile, Breb., a rather 

 small form, found in a Canadian gathering made by Prof. M'Nab on 

 his recent visit. This is far from a common species here at home, 

 but can hardly be called a rarity. It seems to be a constant form, 

 though differing slightly in dimensions. Very few other forms 

 occurred in the Canadian gathering, and none seemingly very note- 

 worthy. A Palmellaceous algal form occurred in the gathering, of 

 which Dr. M'Nab showed a slide. Some of the examples presented 

 the appearance of a slipping out of the protoplasmic contents of 

 certain of the cells en masse ; some seemingly showing this pheno- 

 menon in a more remarkable manner Mr. Archer had met with 

 in some of the material Dr. M'Nab had given him. 



Nostoc calidarium, Wood, from Gei/ser-basifi, Wi/oming, — Dr. E. 

 Perceval Wright showed a few mounted fragments of the gelatinous 

 alga from the Geyser-basin, Yellowstone Park, Wyoming, which had 

 been collected by Mr. Gr. F. Fitzgerald, and exhibited at the previous 

 meeting of the Club. The mass seemed to be composed of a mat- 

 ting together of several algal forms, the prominent species in which 

 was a Nostoc, very possibly Nostoc calidarium. Wood, a species 

 described as found in a thermal spring in the northern portion of 

 Owen's Valley, California, the temperature of the water being be- 

 tween 110° and 120° Fahr., or about the same as that of the water 

 in which the specimens exhibited vegetated. Although the two 

 sets of filaments referred to by Wood were present in the mass, 

 no heterocysts had been detected. The other forms found were a 

 Ghroococcus, pretty generally diffused, and much more sparsely an 

 Oscillatoria, provisionally 0. Frohlichii. 



Aregma (Fhragmidium) obtusum, Link, eocJdbited. — Mr. Green- 

 wood Pim showed Aregma (Phragmidium) obtusum, Link, which 

 occurred on leaves of the " Barren Strawberry " {Potentilla fraga- 

 riastrum), in Hollybrook, near Bray, last autumn. This form is 

 very distinct from those occurring on the bramble, rose, and rasp- 

 berry, one of which was shown for comparison, in being quite obtuse 

 at the apex of the spore and having a very short stalk. It appears 

 rare, this being its first notice in Ireland, but occurring on a small 

 and insignificant plant may probably often escape detection. It is 

 curious that the three closely allied genera Aregma, Xenodochus, and 

 Triphragmium are confined to members of the natural order Bosacese, 

 whilst the extensive series of Puccinias, also nearly related, are 

 found on various natural orders, Rosaceae being almost exempt. 



