1^2o] Setchcll-Gardncr: MelanopJiyceae 401 



1. Pylaiella Bory 



Fronds monosiphonous, composed of a creeping, attaching portion 

 and an erect portion ; creeping filaments irregular, more or less pro- 

 f usety branched, not penetrating the uninjured host ; erect filaments 

 either unbranched or moderately to profusely branched, at times pili- 

 f erous ; chromatophores smooth, regular disks or irregular, more or 

 less united plates, or bands ; zoosporangia formed by direct transforma- 

 tion of assimilating cells of the erect filaments, mostly catenate, usually 

 intercalary, rarely terminal; gametangia similar to the zoosporangia 

 in origin and position, both zoospores and gametes escaping through 

 lateral pores. 



Bory, in Diet, class., vol. 4, 1823, p. 393, vol. 13, 1828, p. 565 

 (original spelling Pilayella) ; Leman, "Pylaiella," in Levrault, Diet, 

 sci. nat., vol. 44, 1826, p. 127. 



The genus Pylaiella was founded by Bory de Saint Vincent in 1823 

 and redescribed by him in 1828. In the first article, the description of 

 the seriate sporangia tends definitely to diagnose the genus, but in 

 the second article, the type species of the genus is designated as 

 Conferva littoralis L., and further indicated as being the Ectocarpus 

 littoralis 8 protensus Lyngbye (1819, pi. 42, C). In every way, there- 

 fore, there is little doubt as to the conception of Bory. Bory has the 

 spelling Pilayella which seems probably to be a purely orthographic 

 error. It seems best to us to keep the species of Pylaiella separate from 

 those of Ectocarpus since the seriate, and largely intercalary, zoo- 

 sporangia differ decidedly from the projecting and solitary zoo- 

 sporangia of Ectocarpus. The gametangia in Pylaiella are, in typical 

 form, also very distinct from those of Ectocarpus. We, at least, basing 

 our opinion on the development and dehiscence, are inclined to regard 

 the gametangia in Pylaiella as seriate, each separate gametangium 

 opening laterally. In Ectocarpus, the gametangia are single, since all 

 the loculi open inwardly and the gametes are discharged through the 

 apex, even dislocating the terminal hair in forms of Ectocarpus sili- 

 culosus which, otherwise, has gametangia at times resembling, super- 

 ficially, the seriate gametangia of Pylaiella. In attempting to arrange 

 the numerous forms of Pylaiella, as found on the Pacific Coast of 

 North America, we have come to the conclusion that at least four 

 species are represented. 



Three subgenera are described under Pylaiella, viz., Eicpylaiella 

 Born., Bachelotia Born., and Panthocarpus Scottsb. The first and last 



