.388 Mr. HassaU's Notices of British Freshwater Conferva*. 



The cause of the variation in the length of the joints has been 

 explained by the discovery of the law which governs the de- 

 velopment of the Confervae generally ; and here, again, ob- 

 servation affords a reason for the difference of diameter ob- 

 servable among the filaments of the species of this genus. 

 The more simple the structure of any plant, the more simple 

 and isolated will be the laws which preside over its ceconomy, 

 and the fewer consequently should be the abnormal conditions 

 to which it is subject. 



New Species. 



Vesiculifera princeps. Filaments of considerable diameter ; 

 cells usually rather longer than broad; spores circular, 

 lying in cells, which in the thickest part of the filaments are 

 scarcely inflated, but are more so near their terminations. 



The above species is to be referred without doubt to the 

 Prolifera composita of Vaucher, which the elder Agardh con- 

 sidered merely to be a variety of his Conferva capillaris. It 

 would appear, however, to be specifically distinct from the 

 Conferva which I regard as the C. capillaris of Agardh. 



I have conferred the name of princeps upon this species, 

 less from the size of its filaments than from its great abun- 

 dance, both in this country and on the continent. The generic 

 and specific names of Vaucher are altogether inapplicable to 

 the species, both conveying false impressions with respect to 

 its reproduction ; thus the specific term composita is derived 

 from a branched parasite which Vaucher observed growing 

 upon it, and which he erred in supposing to be the proliferous 

 offspring. The fact of the parent filament being simple and 

 that of the parasite branched, ought to have saved Vaucher 

 from this error. 



There is a specimen of this species in the herbarium of Dr. 

 Greville, from Caen, put up by M. Chauvin under the name 

 of C. capillaris — var. /3. alternata, Ag. 



Vesiculifera condensata. Filaments of more considerable dia- 

 meter than those of the preceding species ; cells not so long 

 as they are broad. 

 This species I conceive to be the Conferva capillaris of 



Agardh, whose name for it I have been obliged to change, 



inasmuch as it is very distinct from that which is probably 



the true C. capillaris of Linnaeus. 



It is evidently a very rare species, for I have only met with 



one small specimen, procured I believe from the lake in the 



pleasure gardens at Kew. 



