in Rhodymeniciles : II. Delesseriaceae. 195 
arrangement of the spores in the genus Chylocladia , and is 
convinced from all the characters of the wide separation of 
Hydrolapathum from Delesseria. On the other hand, it is 
now clear that in the young condition of the procarp-bearing 
segment, in the remarkable arrangement of the procarps 
along the midrib in this segment, in the structure of the 
carpogonial branch, as well as in the general course of 
development of the cystocarp, there is the closest agreement 
between this species and the typical species of Delesseria . 
And as, from all analogy, the sexual reproductive structure 
affords the safer criterion in the search for affinities, the 
similarities here disclosed must be taken to outweigh any 
dissimilarities appearing in the origin and arrangement of the 
tetrasporangia. On these grounds, therefore, I cannot but 
think that Schmitz’s contention that Hydrolapathum san- 
guineum should be restored to the Delesseriaceae, and even 
to the genus Delesseria , is fully justified. 
D. sinuosa has had a similarly uncertain position. Schmitz 
(’92) was latterly inclined to divide the Delesseriaceae into 
two tribes, the Delesserieae and Nitophylleae, on account of 
differences in the mode of growth of the thallus. But this 
division would involve the inclusion of D. sinuosa among the 
Nitophylleae, and he therefore suggested the adoption of 
Kiitzing’s genus Phycodrys for its reception. 
This is a course which receives strong support from the 
study of the development of its cystocarp. In the true 
Delesserieae the procarps are borne in pairs along the midribs, 
whereas in D. sinuosa they are scattered as in Nitophyllum . 
In the more compact texture of the thallus, moreover, it 
resembles Nitophyllum . In the existence of a well-marked 
midrib with diverging veins it resembles species of Delesseria . 
These characters seem to mark for it a position intermediate 
between Nitophyllum and Delesseria , and the adoption of 
Kiitzing’s proposal would meet the case. 
With regard to the two species of Nitophyllum , N. laceratum 
comes nearest to D. sinuosa. It seems to be premature to 
suggest the occurrence of two carpogonial branches on each 
