482 Mr. G. Barlee 07i some British species of Chemnitzia. 



plication of the cells which inclose the subepidermal gonidia is 

 afforded by the fact that after they have fallen, whitish spots of 

 the same form are left in the place which they occupied, and if 

 the frond be examined with the microscope, it is evident that 

 these spots are destitute of the cortical stratum, and simply 

 formed of the medullai-y central tissue. Bach articulation of the 

 filaments incloses a nucleus or endochrome which gradually swells 

 and divides into four spores. 



"To give you an opportunity of judging yourself of these 

 facts, I inclose a specimen." 



To the above remarks by Dr. Montagne, I take the oppor- 

 tunity of adding, that the Algae collected by Pr. Welwitsch in 

 Portugal, now in the course of distribution by Mr. W. Pamplin, 

 are said to be of considerable interest. The Fungi, which have 

 passed through my hands for determination, comprise several 

 species which exist in few herbaria ; and the seeds of Phsenogams, 

 amounting to more than 200 species, contain many of Brotero's 

 species that will be highly welcome to the cultivators of European 

 forms, and for the most part vegetate with the greatest vigour, 

 as I have now the daily pleasure of witnessing. 



XLIX. — On some British species 0/ Chemnitzia. 

 By George Barlee, Esq. 



To the Editors of the Annals of Natural History. 



Gentlemen, Readiug, May 22, 1851. 



I BEG to offer a few remarks in reply to the paper in your last 

 month's ' Annals,' by my respected friend Mr. Clark, upon the 

 genus Chonnitzia ; and although I have no materials at hand 

 for reference, my books and specimens being at Falmouth, I 

 think I shall be able to supply from memory certain facts, which 

 will satisfy many of yoiu" readers, that as regards two of the 

 species included in Mr. Clark's list, which he proposes to ex- 

 punge from the catalogue of the British MoUusca, he has formed 

 an erroneous opinion. I fully admit the truth of much that 

 Mr. Clark has stated from time to time in your ' Annals/ as to a 

 predisposition with most collectors to originate new species upon 

 insufficient specialties, and more frequently from mere shght 

 variations of form ; — the effect probably of locality, influenced 

 by a variety of causes which seem at present to be scarcely un- 

 derstood or sufficiently appreciated j such as the abundance, 

 scarcity or quality of food, nature of soil, the greater or less 

 purity or strength of water, absence or presence of freshwater 

 streams, sheltered or exposed situation, favouring or interfering 

 with the repose and quiet of the animal, &c. 



