191-1] Setchell: The Scinaia Assemblage 87 



The eystocarp in Scinaia ftircellafa has bet'ii the subject of con- 

 siderable controversy which is so well summed uj) bv Bornet and 

 Thiiret (1876, [>. 1!)). It is a pyriform structure borne just under 

 the cortex throufjh which it opcMis by a distinct carpostome. The 

 jxtint ill dispute was the possession of a ccllulai- envelope. This wa.s 

 pointed out by Moiitagne (1842. ]). 257) but was either passed over in 

 silence (Kuetzing. 184!). p. 715. 18b(i. \)\. 08, b, Harvey. 1846, ])1. 69. 

 tigs. 8 and 7) or denied (J. G. Agardh, 1851, p. 421, and 1876, p. 512). 

 Later it was acknowledged and made plain (Harvey, 1853, p. 136; 

 Thuret. 1855. p. 155; Crouan, 1867, pi. 17. no. 118, fig. 4; Bornet and 

 Thuret, 1876, p. 19, pi. 6. fig. 6. 7.; Schmitz. 1896, p. 337, fig. 206. b; 

 J. G. Agardh, 1880, p. 245) so that there remains no reason for doubt. 

 In some species, however, it seems fairly certain that the envelope 

 consists of fairly distinct filaments whose points are neither enlarged 

 nor combined (consequently) into a pseudoparenchymatous structure. 

 In dealing with dried specimens, however, it is often difficult to settle 

 such a question entirely satisfactorily. 



Concerning the cystocarps in other species of Scinaia little has been 

 said except as to position in the frond (M. A. Howe, 1911, p. 500), 

 yet, as will be shown later, the shape, size and peculiarities of the 

 enveloping tissue show sufficient and constant variations, to afford 

 valuable diagnostic characters. 



Two species have been found which in external appearance have 

 such close resemblance to Scinaia furcellata (as generally conceived) 

 that they would ordinarily be referred to that species, whose cysto- 

 carps are not strictly of the Scinaia-\y\^e, but are more of the 

 Galaxaura type, in that the gonimoblasts, instead of all rising or 

 radiating from a more or less distinct cellular placenta and being 

 free, have some free while some adhere to the walls of the periderm 

 and line the lower half to two thirds of the cystcarpic cavity (cf. 

 pi. 16, fig. 61). It has seemed necessary to remove these two species 

 from Scinaia and even to create a new genus (Psciuloscinaia) to receive 

 them, since the vegetative characteristics are distinctly scinaioid. In 

 all the species of Scinaia and GloiopJdoea, on the other hand, the 

 gonimoblasts in the cystocarps. both of Sci)iaia and of Gloiophloea, 

 arise from a small, but varying placenta, and are all free from the 

 periderm. 



The development of the eystocarp in Scinaia furcellata has been 

 thoroughly described and illustrated by Bornet and Thuret (1876. 

 1>. 20, pi. 6, figs. 1-7). The procarps are alwa.ys formed in the ajiical 



