Cystocarp in Rhodomelacccie (II). 
199 
Laurencia pinnatifida, Lamx. 
The genus Laurencia is, as I have stated earlier, placed 
by Agardh (5) outside the Rhodomelaceae in the family 
Chondrieae. Schmitz (3) has included it among the Rhodome- 
laceae, but placed it in a tribe Laurencieae, distinct from the 
Polysiphonieae, which is made to include Chondria . Chondria 
tenuis sinm, C. A g., is however Laitrencia tenuissima , Grev., of 
the Algae Britannicae (14) and the Phycologia Britannica (4 a). 
I was therefore curious to see what light would be thrown 
upon the relative position of Chondria and Laurencia by the 
comparison of the development of the cystocarp, and I have 
found that the two plants, C. tenuissima and L . pinnatifida, 
exhibit the closest correspondence in the essential elements of 
the cystocarps. In Laurencia the procarps are borne upon 
the ‘ leaves ’ which crowd the depression at the apex of 
growth ; the second joint of these leaves is the one which 
furnishes the essential procarpial structures ; the carpogonial 
branch is four-celled ; two richly-branched tufts of sterile 
filaments exist already at the moment of fertilization of the 
trichogyne ; as far as I could make out, the gonimoblast- 
filaments arise here also directly from the pericentral cell, 
which in that case acts as the auxiliary cell ; and the same 
absorption of neighbouring cells takes place here- as in 
Chondria. The paranematal filaments are, however, still more 
luxuriant in Laurencia than in Chondria , and line the cavity 
four or five cells deep. The wall itself also consists of many 
more layers than is the case in Chondria. Chondria tenuissima 
is an annual plant, and has a thin ‘ cortex ’ compared with 
Laurencia pinnatifida , which is a perennial, and has a ‘ cortex 5 
so deep that its ‘ articulate ’ character is greatly obscured. 
Allowing for this difference of habit, the two plants would 
seem, judging from the structure of the cystocarp, to be very 
closely alliedc It seems to be generally agreed that the 
cystocarp in Rhodomelaceae usually presents such uniformity 
that generic characters cannot be founded upon characters 
derived from it, and while the great similarity of Laurencia 
