136 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Sect. II. Fronds icithout spines, cortical cells confined to a definitely lim- 

 ited band round the nodes, the internsdes diaphanous. 



0. diaphanum, Both ; Phyc. Brit., PL 193. 



Fronds brownish red, filaments two to four inches high, loosely tufted, 

 main branches setaceous, rather stout, distantly forking, beset with short, 

 lateral, dichotomous branchlets, apices incurved ; tetraspores immersed, 

 in whorls at the nodes ; favellse lateral, involncrate. 



Nahaut, New Bedford, Mass.; Providence, B. I.; New York Bay, 



Harvey; Europe; California. 



The localities given are quoted from the Nereis. As far as our own experience goes, 

 the present species is of very infrequent occurrence on the New England coast, 

 although we have specimens collected at Lynn, Mass., and others from the vicinity 

 of New York, collected by Mr. A. R. Young, which may possibly be referred to C. dia- 

 phanum. In almost all cases the C. diaphanum of American collectors is the C. strictum 

 of the Phycologia Britannica a species closely related to the present, and agreeing with 

 it in the fructification, but differing in ramification. C. diaphanum has rather stout 

 leading branches, which are beset with secondary dichotomous branches which are 

 alternately given off from the main branches, and which are much finer than the main 

 branches, the tips being capillary. The general outline of the frond is pyramidal, and 

 that of the principal branches and their ramifications is oval-elongated. In C. 

 strictum there are no leading branches, but the filaments are of a pretty nearly uni- 

 form diameter, regularly dichotomous throughout, and form globose tufts. Both 

 species differ from our other species, except C. Hooperi, in being of a brownish-purple 

 rather than of a distinctly rose- colored tint, and both adhere closely to paper in drying. 



0. strictum, (Kiitz.) Harv. (C. strictum, Phyc. Brit., PI. 334. — Gon- 

 groceras strictum, Kiitz.) 



Fronds brownish red, filaments capillary, two to six inches high, 

 densely tufted, branches uniformly dichotomous throughout, divisions 

 erect, fastigiate above, apices forcipate ; tetraspores immersed, whorled 

 at the nodes. 



On Zostera and other marine plants. 



Common from New York to Cape Cod. 



This species forms large tufts at the base of Zostera in warm, shallow bays, and ia 

 often in company with Polysiplwnia Olneyi. In the Little Harbor at Wood's Holl it 

 is found in large quantities, after a heavy blow, lying unattached on the mud, just 

 below low-water mark. 



C. Hooperi, Harv. (G. Hooperi, Harv., Ner. Am. Bor., Part II, 

 p. 214. — G. Deslongchampsii, Farlow, in Report U. S. Fish Comm., 1875.) 



Fronds dark purple, one to four inches high, filaments procumbent 

 and densely interwoven at base, above dichotomous, with short, erect, 

 irregularly placed lateral branches, apices straight, erect, cortical cells 

 forming a sharply defined band at the nodes, axile cells short above, 

 becoming twice as long as broad below ; rhizoidal filaments unilateral, 



