236 PROCEEDINGS OF SOCIETIES. 



(who was absent) Mr. Archer showed examples of that somewhat 

 remarkable desmid Penium (Oosmarium, Autt.) curium, Breb. 

 These specimens were taken by Mr. Crowe from a shallow acci- 

 dental water-deposit on the railway platform at the Bray station, 

 thus showing the somewhat capricious distribution of this form, 

 seemingly always occurring so far away from its congeners, the 

 Desmidieae at large, delighting, as they do, in boggy and mossy 

 localities, not roadside ruts ! Mr. Crowe had taken it on a former 

 occasion on a roadside in Wales ; again, scarcely a step from his 

 own halldoor at Bray ; and Mr. Archer on the roadside near 

 Dargle Gate. This kind of habitat seems to accord with de Bre- 

 bisson's description of that of Cosmarium Regelianum, (Nag.) 

 Breb., seemingly equivalent to P. curtum, Autt. (though de Bre- 

 bisson records both as distinct) ; the former, at least, occurs, he 

 says, " tapissant des cavites sablonneuses, recemment inondees par 

 la pluie." 



Sporocyhe lyssoides. Fries, exhibited. — Mr. Pirn showed 

 Sporocybe byssoides, Fries, which grew on a decaying bulb 

 of Sophronitis grandijlora ; the dense heads of brown, minutely 

 echinulate spores were very characteristic. 



Structure of petioles in the genus NympJicea. — Mr. Mackintosh 

 laid before the Club the results of some further examinations of 

 the structure of the petioles in Nymphsea. Through the kind- 

 ness of Dr. Moore, Director of the Grlasnevin Botanic Gardens, 

 he had obtained specimens of eight species, which he had found 

 could be arranged in two groups. One of the groups, of which 

 Nymphcea alba might be taken as the type, was characterised by 

 having more than two primary air-passages of subequal size, 

 and were provided with stellate cells. The other section, repre- 

 sented by Nymphasa Devoniana or N. dentata, had two large 

 primary air-paspages, several smaller secondary ones, and no 

 stellate cells. Mr. Mackintosh exhibited sections of three species 

 of the latter group — N. lotus, N. Devoniana, and iV. thermalis — in 

 order to draw attention to the only difference which he could 

 detect in the different species : this consisted in the septum 

 between the two primary air-passages being made up of two, 

 three, or four cells. It might as yet seem doubtful if any depend- 

 ence could be placed on a character of apparently so trivial a 

 nature, but further investigation which he hoped to pursue 

 would doubtless throw light on this interesting subject. — He 

 likewise showed a cross section of the petiole of N. lotus, in which 

 two or three of the cells bounding one of the secondary air- 

 passages had become hypertrophied and grown out into a cel- 

 lular mass which nearly filled up the cavity. 



A JPseudo- Cosmarium — in other ivords, a Cosmarium-like excep- 

 tional state of an Arthrodesmus-incus-form — exhibited. — Mr. Archer 

 drew attention to what at first blush looked like a new Cosmarium ; 

 and though this, as will be seen, was not so, he had actually labelled 

 the bottle in which it occurred, in order to distinguish it from others, 

 " Cosmarium inquirendum." This little form was very minute, of 



