Botanical Society of Edinburgh. 519 



cavity and brought in contact with the air, without the intervention 

 of any true vascular system. 



The beautiful transparency of the animal, and the facility with 

 which the development of the ovum may be traced through all its 

 stages, induces the author to believe it to be well-suited to the in- 

 quiries of the embryologist and of those who devote themselves to 

 the study of the metamorphosis of cell into tissue. 



This animalcule has hitherto been discovered only in a few situa- 

 tions (in Norfolk near Norwich, and in Warwickshire near Coven- 

 try), but it is believed, from the very general dispersion of Infusoria, 

 that it may be more extensively met with, especially in the months 

 of June, July, August and beginning of September. 



The author concludes by expressing his belief that re-examina- 

 tion of the whole order of Rotifera is necessary to determine the 

 disposition of the sexes, and to assign them their proper situation in 

 the scale of animated beings. 



BOTANICAL SOCIETY OF EDINBURGH. 



May 10, 1849. — Professor Balfour, President, in the Chair. 

 The following communications were read : — 



1. "Description oi Monormia, Berkeley," by G. H. K. Thwaites, 

 Esq., communicated by John Ralphs, Esq. This genus is allied to 

 Trichormus, Allman, differing principally, if not solely, in its definite, 

 linear frond, which encloses a single moniliform filament to be traced 

 throughout all the peculiar convolutions of the frond. The vesicular 

 cells are interstitial, and occur singly. The sporangia are numerous, 

 and are first formed from the cells at the greatest distance from the 

 vesicular cells. Without due attention Monormia might easily be 

 mistaken for a species of Nostoc ; but the mass formed by its con- 

 voluted frond is not enclosed by a common membranous pellicle as 

 in that genus. 



Monormia intricata occurs in slightly brackish waters in floating 

 gelatinous masses, each about as large as a walnut, and usually of a 

 reddish brown colour. 



The paper concluded with a synoptical table of the genera of 

 NostochinecB, and will appear in the ' Annals of Natural History ' and 

 the Society's Transactions. 



2. " On the Causes which determine the Limits of the different 

 species of Vegetables in the North of Europe," by Robert Huish, Esq., 

 F.L.S., communicated by William Wallace Fyfe, Esq. In this com- 

 munication Mr. Huish gave a condensed view of the researches of 

 M. Alphonse DeCandolle in this interesting department of botanical 

 science. 



Dr. Balfour exhibited plants of the following interesting species 

 from the Royal Botanic Garden, and made remarks upon them, viz. : 

 Trichopilia tortilis ; Maxillaria Harrisonii ; Oxalis bupleurifolia, a 

 shrubby species from Brazil ; Cereus crinitus ; Pinguicula grandiflora, 

 distinguished by the large size of the flower, length of spur and con- 

 tinuity of the segments of the corolla ; Xylophylla laiifolia ; Persea 



