Tin: MARINE AIa.J: of new ENGLAND. 135 



tips ol' the Itrnmlu's. Tho grnns has been split up into a nnnilur of «liiUrrnt ^mera 

 l»y KUtzin«:, Vuit hy most writers his «livisions are only aeoeptecl as snh^tnrra. Sterile 

 s|K?eiuieus are not rasily detenninecl an<l it is always desirable to have trtrasporic 

 plants. Although wr have an ahnnilanee of the j;enus on our eoast, the nunilur of 

 species is eoniparativrly small, an«l the gnmp of species having spines at the notles is, 

 as far as is known, <|uite wanting. 



Sect. I. Fromls without spines, cortical cells decurrent from the nodes und 

 more or less completely covering the internodes. 



C. RUBKUM, \g:. (C. rubrnm, Phyc. Brit., PI. 181.) 



Fronds robust, dichotouious, siibfiisti^iate, branches erect, apices in- 

 iirved or forcipate, nodes contracted below; tetraspores in irregular 

 series at tlu* nodes, immersed; favelhe lateral, solitary, witli a short in- 

 volucre. 



Var. ruoLiFKKUM, Ajj;'. [C. hotryocarpum, Phyc. Brit., PI. 21.j.) 



Fronds beset on all sides with numerous, lateral, simple or forked 

 1 »ranchlets. 



Var. SECIINDATU3I, Ag. 



Bmnchlets oenerally secund. 



Var. st^UARKOSUM, Uarv. • 



Fronds small, regularly dichotomous, fastigiate, with very few, short, 

 lateral branchlets, lower divisiims distant, spreading, upper divisions 

 close together, widely spreading, apices often revolute. 



Everywhere common; var. squarrosum on Zosfcra, ^lassachusetts Bay. 



A ubiquitous and variable species, of which we have enumerated only the principal 

 • -nns. The typical form is easily recognized, and the same is true of most of the va- 

 I Mties. The var. decurrens has the internodes partly naked, especially in tho upper 

 part. The var. (hTtimns of the Nereis is referred by Agardh to the next species, 

 and is distinguished from the true var. (kcurrens of C. nt^rwrn, which has immersed. 



' tr.ispores, by the large tetraspores arranged in a regular circle at the nodes and i)ro- 



' ctiug decidedly above the surface. 



C. CIRCINNATUM, KUtz. 



Fronds setaceous, dichotomous, fastigiate, divisions erect, patent, 

 apices forcipate, internodes partly corticated by the cells which are de- 

 urrent from the nodes; tetraspores large, projecting in a ring around 

 lie ni)per nodes. 



Glencove, L. I., Mr. Young ; Dartmouth, Mass., Miss Ingraham ; Mag- 

 nolia, Mass., Mrs. Jinig. 



Agardh, in his EpicriMs, reA'rs to the present species the C. decurrens of Harvey ( Phyc. 

 lirit., PI. "S7i'>), which in the Nereis Am. Bor., is made a variety of C. ntbritm. There is 

 a var. decurretiM of ('. ruhrum w hich is admitted by Agardh, which, if we understand 

 correctly, has small immersed tetraspores. This form occurs also with us, but wo 

 have no notes as to the locality. To the present species we refer fornjs in whi«h tho 

 npper internodes are scarcely corticated at all an<l in wbirb the larire. jirojectiiig tet- 

 ra«IK)res are in a single ring at the upper nodes. 



