lOG PROCEEDINGS OF SOCIETIES, 



almost like a hyaline, mucb crumpled membrane, having lost its 

 granular aspect. 



21st September, 1876. 



Sections of Leptogium tremeTloides,exliibited. — Mr. Pim showed 

 examples and some instructive transverse sections of Leptogium 

 tremelloides as identified by Rev. W. A. Leighton. The preparation 

 showed the upper and lower cortical layer toconsistof.in this aspect, 

 nearly square cells between which were the phycochromaceous 

 more or less moniliform strings ofgonidia and the hyphae. Viewed 

 vertically the cells of the cortex were of irregular figure and 

 closely set. One section passed through what was apparently 

 an apothecium from which the asci had fallen. 



Structure of Sheath of Spine of Goniocidaris geranioides, Lamk. 

 — Mr. Mackintosh showed a cross section of the spine of Goni- 

 ocidaris geranioides, Lamk., and drew attention to the nature of 

 the external sheath, which is composed of reticulated tissue, with 

 very wide interspaces, instead of the ordinary solid calcification 

 with simple tubes which occurs in all the Cidaridse, as far as he 

 had observed. This peculiarity does not seem to be shared by 

 the species of Goniocidaris. 



Undescrihed Species of Craspedodiscus. — Eev. E. O'Meara 

 showed a diatomaceous form appertaining to the genua Craspe- 

 dodiscus, which he considered as yet undescribed. It difi'ers from 

 Craspedodiscus coscitiodiscus in having the areoles of the interior 

 portion of the disc much larger than in the marginal portion. 

 The example was found in fossil earth from Delaware, Maryland, 

 U.S.A. In case the form is not described, Mr. O'Meara would 

 suggest the specific name of Ma?y!andicus. 



A Puzzling Desmidianform. — Mr. Archer showed examples of a 

 seemingly unicellular (non-filamentous) algal form, not unlike a 

 joint of Gonatozi/gon Brebissonii, but smooth, not asperate. To 

 a great extent it had the aspect of yet another companion-form 

 for that named Closterium obtusum by de Brebisson. His friend 

 Mr. Roy, of Aberdeen, to whom he had submitted fresh specimens, 

 seemed to regard it as a very distinct thing indeed, but Mr. 

 Archer must say he still remains in considerable hesitation. Per- 

 haps more of it on a future occasion. 



