THE MARINE ALQM OF NEW ENGLAND. 129 



Wo have only quoted the localities given by Harvey, although we havo found what 

 •we take to be C. corymbosum at Newport, Wood's Holl, and in considerable abundance 

 at Nahant, always growing on Zostera. An examination of the different published ex- 

 siccataB of European writers would lead one to think that several different species had 

 been included under the name of C. corymbosum. One might doubt whether the form 

 of Crouan, No. 139, and Areschoug, No. 15, belong to the same species. At Nahant the 

 same form occurs as that distributed by French algologists. 



C. Dietzls], Hooper. 



" Fronds capillary, pellucidly-articulate nearly to the base, the lower 

 part percurrent, distichously-pinnate, stem veiny, branches alternate, 

 simple, set at each node with short, alternate, subsimple or pinnato- 

 dichotomous plumules, and often terminated by a dense fascicle of 

 ramuli, rachides zigzag; articulations of the stem six or eight times, 

 of the rachides three or four times, of the ramuli eight or ten times as 

 long as broad ; apices subattenuate, obtuse, or subacute ; tetraspores 

 elliptical, tripartite, solitary on the uppermost ramuli." (Ner. Am. Bor., 

 Part n, p. 236.) 



Greenport, Mrs. Diets. 



Only known through the description given by Harvey in the Nereis. Harvey states 

 that it is related to C. corymbosum and C. versicolor. The specimens referred to Wood's 

 Holl in Proc. Am. Acad. , 1875, p. 376, were probably incorrectly determined. 



Subgestus SEIROSPORA, Harv. 



Fronds erect, main branches corticated j antheridia in tufts on the 

 outer side of short branches; tetraspores tripartite; bispores and seiro- 

 spores present ; cystocarps destitute of enveloping jelly. 



O. SEnt'osPERMTOi, Griff. (Seirospora Griffithsiana, Harv., Phyc. Brit., 

 PI. 21. — Phlebothamnion seirospermum, Kiitz. — C. versicolor, var. seiro- 

 spermum, Harv., in Hooker's Journ. Bot. ; Pcecilothammon seirospermum, 



T$3dg.) 



Fronds dioecious, capillary, two to six inches high, pyramidal in out- 

 line, main axis percurrent, pinnate with alternate, undivided, lateral, 

 branches, which bear secondary branches beset with delicate, erect, 

 dichotomo-multiiied, corymbose branches, main branches corticated, 

 smaller branches monosiphonous and byssoid ; antheridia in tufts on 

 the outside of short branchlets ; tetraspores tripartite, sessile on the 

 upper branchlets, sometimes replaced by bispores ; seirospores oval, in 

 moniliform tufts at the ends of the branches ; cystocarps composed of 

 radiating chains of spores without gelatinous envelope (Bornet.) 



On Zostera, shells, and stones below low- water mark. 



Common throughout Long Island Sound ; Salem, Mass., Hcvrvey. 

 S. Miss. 59 9 



