■ 177 



The sporangia are cylindrical or somewhat clavate and dis- 

 persed between them we find the club-shaped paraphyses some- 

 times rather numerous, sometimes very scarce or even wanting. 

 According to Mitchell the paraphyses originate from the basal 

 cell of the sporangia and therefore are not formed until after the 

 disappearance of the sporangia. As to this I must point out that 

 I have found paraphyses scattered also between the plurilocular 

 sporangia in the sori (see Fig. 138). 



It is a common species and occur mostly in sheltered or not 

 much exposed places in shallow water. 



Geogr. Distrib. Widely distributed in all warmer seas so far north 

 as to the south coast of England. 



Hydroclathrus Bory. 



1. Hydroclathrus cancellatus Bory. 



Bory, Diet, class. VIII, p. 419 (non vidi). Harvey, Phycologia Austra- 

 lica, pi. 98; Nereis, p. 120, tab. IX A. Mitchell, M., in Murray, Phyc. 

 Memoirs, p. 53, pi. XV, fig. 2—4. Thuret, G. et Ed. Bornet, Etudes 

 phycologiques, 1878, p. 12—13. Vickers, A., Phycologia Barbadensis, 

 Part 11, pi. 23. 



Asperococcus cancellatus Endl., Mantissa Botanica altera, Suppl. 3, 

 1843, p. 26. 



Halodictyon cancellatum Kiitz., Phycologia generalis, 1843, p. 336. 



Encoelium clathratuni Ag., Spec. Alg. p. 412. 



Stilophora clathrata Ag. in "Flora", 1827, p. 642. 



Asperococcus clathratus J. Ag., Spec. Alg. I, p. 75. 



In "Etudes Phycologiques", 1. c, Thuret and Bornet have 

 pointed out that while the sporangia entirely cover the surface 

 of the young plants the old specimens with the well known 

 peculiar reticular appearance 

 are quite sterile with the 

 exception of some few spo- 

 rangia occurring now and 

 then near the groups of 

 hairs. Having only collected 

 old specimens mine, in 

 accordance with this obser- 

 vation, were sterile ; even 

 near the hair groups I have 

 not succeeded in finding Fig. 189. Hydroclathrus cancellatus Bory. 

 sporangia. Transverse section of the thallus showing 



. . ^ , - rhizoids growing out from the surface 



As pomted out by cells. (About 170 : 1). 



