40 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



stalks upon wliicli tliey are growing. It first appears as solid green spots upon the 

 Fucus, which soon swell out into thin bladders, which partly collapse on being 

 removed from the water. The peculiar inverted V-shaped filaments are seen to greater 

 advantage by dissecting with needles small pieces of the frond than by making sec- 

 tions with a razor. 



The only other species of this genus is Rormactis Balani, Thuret, which grows on 

 T3arnacles on the coast of France. It is a comparatively minute plant, much less 

 striking than our own species, which seems rather to replace, on our coast, the Rivu- 

 laria niiida, Ag., of the coast of Europe, which it resembles in general appearance 

 and habit. The external resemblance to that species is so great that specimens were 

 sent to Dr. Bornet as It. nitida, Ag. (?) By him it was recognized as a new species 

 of Hormactis, H. Farloicii, under which name it was distributed in Alg. Am. Bor. 

 Since then Dr. Bornet has recognized its identity with Fdvularia Qnoyi, Ag., of the 

 Marianne Islands. It is not a little remarkable that the si^ecies is only known in two 

 localities so widely remote from one another. 



Stigonema mamillosum, Ag., occurs in a brook which empties into the sea at 

 Rafe's Chasm, Magnolia Cove, in Gloucester ; and Calothrix parietina, Thuret, is 

 found in Nobska Pond, close to the sea, at Wood's Holl. The species named all belong 

 in the present order, but are not strictly marine. 



Order ZOOSPORES 



Algae either green or olive-brown in color. Eeprodiictiou by means of 

 zoospores, which unite in pairs to form a zygospore. 



This order includes all the marine CJorosjjermece attributed to New England in the 

 Nereis Am. Bor., with the exception of the genus Vaucheria, as well as the greater 

 part of the olive-brown sea-weeds, with the exception of the rock-weeds or Fucacew. 

 The account of the order given in the introduction to the present article should bo 

 consulted in the present connection. 



a. Green algae, multicellular, zoospores of two kinds — macrozoospores 



with four and microzoospores with two terminal cilia . . Chlorosporece. 



h. Green algse, frond unicellular, branching Bijopsidece. 



c. Green algae, frond unicellular, simple , Botrydiece, 



d. Olive-brown algae, zoospores of one kind, with two cilia laterally 



attached Phwosporece. 



Suborder CHLOROSPORE^. 



1. Fronds membranaceous ( Ulvce) 2 



Fronds filamentous 3 



2. Cells in a single layer Monostroma. 



Cells in two layers Ulva. 



3. Some of the cells furnished with long hyaline hairs Bulhocoleon. 



Cells destitute of hyaline hairs 4 



4. Filaments branching throughout Cladopliora. 



Filaments with short, root-like branches only Bhizoclonium. 



Filaments unbranched 5 



5. Filaments rigid, setaceous ClmtomorpJia. 



Filaments soft and flaccid Ulothrix. 



