Mr. Hassall's Notices of British Freshwater Conferva*. 343 



lopments of the external corpuscles (spores or seminules) re- 

 sulting from a concentration of the green matter; and for 

 the purpose of establishing the series of developments of zoo- 

 spores and of spores properly so called, they have represented, 

 it appears to me, these bodies of very different sizes. They 

 have amplified the first and diminished the second in such a 

 manner as to present them of nearly the same volume. I 

 think that I am able, in support of my opinion, to refer to the 

 text and the figures of the Memoires of MM. Agardh and 

 Morren inserted in this work." 



" The first of these learned men appears, indeed, to have 

 comprehended the difficulty of explaining the development of 

 two sorts of reproductive bodies, since he admits in certain 

 cases the disintegration of spores into numerous sporules en- 

 dowed with a very rapid movement, that is to say, into zoo- 

 spores." 



To the group Vesiculaspermcs are to be referred all the true 

 Confervae ; but before admitting any species as such, it is 

 necessary that it should undergo a rigorous examination, for 

 we find placed among the Confervae proper many species 

 having no relation whatever with those near to which they are 

 located, but are referable to some other of the genera, be- 

 longing to other groups already established. Thus Conferva 

 alpina, C. purpurascens, C. zonata, C. ericetorum, C. mucosa 

 and C. punctata, are placed by Agardh the elder and Harvey 

 amongst the Confervae properly so called. The first two are 

 nevertheless Conjugates, belonging to the genus Mougeotia ; 

 the third a Sphceroplea ; and the fourth ought, in my esti- 

 mation, to be referred to the branched species of Confervae ; 

 while C. mucosa and C. punctata form the types of a distinct 

 genus. *> 



I have been so fortunate as to discover the exact characters 

 presented by some of the species when in a state of repro- 

 duction, which have been correctly considered as true Con- 

 fervae; and so different is the appearance of these, when in 

 that state, that considerable difficulty is experienced in recog- 

 nizing them, by the descriptions of their discoverers, for the 

 species, of which they intended to convey accurate definitions. 

 Nevertheless, the characters furnished by species in a state 

 of reproduction are almost the only ones to be depended upon 

 as of specific importance. These species are, Prolifera com- 

 posita of Vaucher, C. vesicata of Muller *, and C. bombycina 



* M. Decaisne appears to have seen the spores in this species, and to have 

 understood the mode of their formation, viz. by the intermingling of the con- 

 tents of two adjacent cells in the same filament, and hence was induced to 

 place it amongst the Syrispores, overlooking the many important points no- 



