28 EEPOET OF COMMISSIONER OF FISH AND FISHERIES. 



of Marine Algse, 1876. — Pleurococeus, Bait., Flora Europ. Alg., Sec. Ill, 

 p. 25.) PI. I, Fig. 1. 



Cells spheroidal, yellow, about .0035 mm to .005 mm in diameter, im- 

 bedded in an olive-brown gelatinous stratum, occasionally single, usually 

 united in twos or some multiple of four. 



Eastport, Maine; Gloucester, Mass.; Newport, E. I.; northern coast 

 of France. 



We found this species abundant in October, 1875, on tbe wharves of Eastport., where 

 it formed thin gelatinous layers of a dark-brown color at high-water mark. It prob- 

 ably occurs at high-water mark on wharves along our whole coast. This species is said 

 by Thuret to form the gonidia of Yerrucaria haloclytes, Nyl., a species which we are 

 informed by Prof. Tuckerman is not known to lichenologists in this country. In 

 the present species the concentric layers of the gelatinous envelope of the cells is 

 wanting. The color of the cells is quite constantly brownish yellow, but occasion- 

 ally they become dark green. The average diameter of the cells in American speci- 

 mens seems to be slightly less than Thuret's measurement. 



POLYCYSTIS, Kiitz. 



(From nohvc, many, and kvctic, a bladder.) 



Cells spherical, densely aggregated, united by an intercellular mucus 

 into solid masses. 



In this genus we include Microcystis of Kiitzing, in which the colonies are isolated 

 and not united in botryoidal masses, one being evidently an immature state of the 

 other. 



P. elabens, Kiitz. (Microcystis, Kiitz., Tab. Phyc, Vol. I, PI. 8, 

 Fig. 1.) . 



Cells bluish green, oblong, about .004 mm in diameter, closely packed 

 in solid colonies, which are aggregated in botryoidal masses. 



Wood's Holl, Mass.; Europe. 



Common in summer on decaying alga3, over which it forms slimy masses, mixed with 

 species of Lyngoya, Microcoleus, &c. 



P. PALLIDA, (Kiitz.). 



Cells bluish green, oval, .005-7 mm x .007-9 mm . 



Newport, E. I. ; Gloucester, Mass. ; Europe. On Cladojphorce and Zo8- 



tera. 



Differs mainly in the size of the cells from the preceding species. Our form agrees 

 closely with European specimens. 



CLATHEOCYSTIS, Henfrey. 



(From Klydpov, a lattice, and Kvorig x a bladder.) 



Cells minute, very numerous, imbedded in mucus, forming a colony 

 which is at first solid, then hollow, and finally perforate. 

 C. ROSEO-PEESiciNA, Cohn, in Beitriige zur Biologie, Yol. I, Part III, 



