1914] Setchell: The Scinaia Assemblage 93 



shows, these slender colored cells of the epidermal layer are abundant. 

 Crouan a867. pi. 17. fig. 118) and Bornet and Thuret a876, p. 20) 

 indicate that they also find them abundant. The g^o^vth of the 

 peripheral filaments in Scinaia, and aLso in the related genera to be 

 considered in this account, is corjinbose and eymose. The central cell 

 of the cluster ceases to grow and becomes a utricle, while the lateral 

 cells grow on into the slender, colored cells f cf. also Bomet and Thuret, 

 loc. cit.). A similar growth is to be found in .species of the genus 

 Gloiophloea J. Ag. as wiU be shown below, but in the species of the 

 latter genus the process proceeds farther than it does in species of 

 Scinaia. 



The antheridia are developed from the .slender, colored cells of the 

 epidermal layer. These cells bear one to four antheridial cells, or 

 may bear one to four branches, each of which, in turn, bears one to 

 four antheridial cells ''cf. figs. 1. 6. 7. and 8 on pi. 10). It is 

 difficult, as Bornet and Thuret say (1876, p. 20), to make out the 

 exact antheridial structure and it was only in the thinnest sections 

 that the details could be at all clearly perceived. In vigorous plants 

 of Scinaia furceUata they are verj' abundant. 



The structure and development of the cy.stoearp in Scinaia fur- 

 ceUata must also be carefully considered because this .species is the 

 type of the genus. The development has been carefully and most 

 accurately described by Bornet and Thuret (loc. cit., p. 20. pi. 6. 

 figs. 1-5). The carpogonium gives rise to a glomerule of cells from 

 which the gonimobla.sts arise, while the cells of the carpogonial branch 

 immediately below the carpogonium send out a dense circle of brac- 

 teoid filaments which grow up around the developing gonimoblasts. 

 As these bracteoid filaments develop, the cells of the lower two-thirds 

 become swollen and are consequently pressed together and adhere to 

 form a pseudoparenchymatoiLs periderm, while the cells of the upper 

 third remain distinct and filamentous, in the region of. and surround- 

 ing, the carpastome. The filaments of the periderm .send off slender 

 free branches into the cavity- of the cystocarp. The gonimobla.st fila- 

 ments branch and form a broader or narrower ovoid and very compact 

 mass. The spores are elongated ellipsoidal successively abjointed above. 



The type locality of Scinaia furceUata is Sheringham. in Norfolk. 

 England, on the North Sea. whence it was described by Turner (1801) 

 as Ulva furceUata. Through the kindness of the Director of the 

 Royal Botanical Gardens at Kew. a search for the type specimen was 

 made by Mr. A. D. Cotton, at my request, and what seems, in all 



