THE MARINE ALG.E OF NEW ENGLAND. 27 



colouies. Intercellular substance generally forming concentric 



layers around the cells (thvoca2)sa. 



3. Cells united in colonies of definite shape. 



a. Cells arranged in the form of an irregular spherCj which becomes 



linally hollow and net-shaped Clathrocystis. 



h. Cells arranged in several layers forming a solid spheroidal body. 



roUjciiHtla. 

 . Cells united in branching dendritic masses Entophijsalis. 



CUROOCOCCUS, Xirg. 



((From xpoo^j the color of the body, and kokkoc, a born-.) 



Cell division taking place in all directions, cells spherical, solitary, 

 or united in twos or some multiple of two, free, /. c, not united into 

 families by means of an intercellular substance. 



According to Nirgeh, the principal distinction between Chroococctis and Glococapsa 

 lies in the fact that in the former genus the cell-wall is thin, while in the latter it is 

 thick and formed of concentric layers. This difference, however, is not constant, as in 

 Chroococcus turgidus the cell-wall is comparatively thick, whereas in Glococapsa crcpi- 

 dinitm the cell-wall is reduced to a minimum. A more characteristic distinction seems 

 rather to be the existence of an intercellular substance in Glococapsa which binds the 

 cells together, but which is wanting in Chroococcus. 



C. TUBGEDrs, XcTg. * {ProtococcitSj Kiitz., Tab. Phyc, Vol. I, PI. G, 

 Fig. 1. — Hcvmatococcus linaJis^ Ilassal, Fresh-water Algii^, p. 331, PI. 

 82, Fig. 2.) 



Cells bluish green, oval, usually single or binate, about .02™°' to 

 .025'"'" in diameter, surrounded by a thick cell -wall. 



Cape Ann, Mrs. A. L. Davis; Europe. Fresh water and marine. 



Found on slimy rocks and piers upon which species of Calothrix, Li/nghtja, &c., aro 

 growing. Probably common throughout New England. The size of the cells varies 

 verj' much. What we have given above is an average measurement. 



GLCEOCAPSA, (Kiitz.) Xirg. 



(From y?.oioCf sticky, and xci/'r:, a box.) 



Cell division taking place in all directions, cells spherical, with thick 

 walls, solitary or united in families, which are surrounded by a gelatin- 

 ous substance which is generally in concentric layers around the cells. 

 Spores known only in G. stcgophila^ Itzigs. (0. Itzigsohniij Bornet mscr.). 



This genus, if we adopt the views of the advocates of Schwcudener's theory, forms 

 the gonidia of the lichen genera Syualissa, Omphalaria, &c. 



G. CREPIDINUM, Thuret, Notes Algoh>giques, p. l', IM. I, Figs. 1-3. 

 (Protococcus, Thuret, in Mem. Soc. Xatur. Cherbourg, Vol. II, p. 388 j 

 Le Jolis, Liste des Algues Marines de Cherbourg, p. 2oj Farlow, List 



