THE MARINE ALGJE OF NEW ENGLAND. 61 



Suborder PILEOSPORE^. 



^Reproduction by means of olive-brown zoospores which have two 

 laterally attached cilia ; sporangia of two kinds — unilocular, containing 

 a large number of zoospores, and plurilocular, compound sporangia, each 

 cell of which contains a single zoospore; conjugation of zoospores known 

 in a few species; marine plants, of an olive-brown color, whose fronds 

 vary greatly in structure, but which all agree in reproducing by zoospores. 



A large group, first correctly defined by Thuret. Previous writers had regarded the 

 structure of the frond to the exclusion of the organs of reproduction, and the species 

 here included were placed in different orders. In the Nereis they were placed partly 

 in the Dictyotacece, Sporochnacece, Laminariacece, Chordariacece, and Eciocarpacece. The 

 four last orders have been kept as families, but the true Dictyotacece are a distinct order. 

 All the olive-brown sea- weeds of New England, except the rock- weeds, belong to the 

 present suborder. In no order of plants do the species vary so widely in habit as in 

 the present. A large number, as the Ectocarpi, are filamentous and resemble in habit 

 the Cladophorw. The Luminance have expanded flat fronds, and in Macrocystis and 

 Egregia, the most highly organized of the order, there are stems, distinct leaves, and 

 air-bladders, and in Egregia special fructiferous leaflets. Many of the species are of 

 microscopic size, but Macrocystis grows to be several hundred feet long. 



SP1LENOSIPHON, Reinsch. 

 (From atpijv, a wedge, and aupuv, a tube. ) 



Fronds formed of single cells placed side by side so as to form a more or less cohe- 

 rent mass ; cells pyriform-cuneate or oblong-elliptical ; contents of cells transformed 

 into a number of very small spherical bodies (zoospores ?). 



In the Contributiones ad Algologiam et Fungologiam, Reinsch places the genus 

 Sphcenosiphon, of which he describes nine species, in the order Melanophycece. One of 

 the species occurs in fresh water and the rest are marine. They all form minute spots 

 on other algse, and consist simply of cells placed side by side, the whole forming a thin 

 membranous expansion. If the small bodies described and figured by Reinsch in the 

 interior of the cells are really zoospores, and if the cells themselves are olive-brown, 

 we must regard the genus Sphcenosiphon a,s the lowest of the Phceosporece. The develop- 

 ment of the zoospores has not been observed, and as Reinsch describes the color of 

 some of the species as bluish green and rose-colored, we must consider the position 

 of the genus to be in doubt. Species of Sphcenosiphon are not unfrequent on our coast, 

 but they have not yet been sufficiently studied. " Those which we have seen are more 

 like the Cyanophycece than the Phceosporece in color. The following descriptions, which 

 may apply to some of our species, are taken from Reinsch, 1. c. 



S. smaragdinus, Reinsch, 1. c, PI. 35, Fig. 4. 



Cells pyriform or broadly cuneiform, rounded at the apex, prolonged at the base 

 into a hyaline pedicel; cells .0168-333 mm long, .0084-112 ram broad at apex, .002 mm at 

 base ; color bluish green ; base hyaline. 



On Plocamium coccineum, Labrador. 



On Polysiphonia, Anticosti. 



S. OLIVACEUS, Reinsch, 1. c, PI. 36, Fig. 2 a. 



Cells pyriform or cuneiform, broadly rounded at apex, contracted at base ; color 

 olive-green; cells .013-24""" long, breadth .OO^e-lCS™" 1 . 



On Ceramium ruhrum, Anticosti and Labrador. 



S. ROSEUS, Reinsch. 



Cells broadly ellipsoidal, placed loosely together, and surrounded by a thick hyaline 

 mucus; rose-colored; .0041-50 mm long, .004-5 mm broad. 



Oft zoophytes, Labrador. 



