THE MARI>re ALG^ OF NEW ENGLAND. 91 



cylimirical ; tVuctificatiou in broiul bauds or largo irregular spots, or 

 i>cc«asionally covering tlu» whole surlaee of frond, composed of large 

 broadly clavatc or wedge-shaped ])arai>hyses aud oval unilocular spo- 

 rangia. 



Fronds cylindrical Chnrda. 



Fronds with a midrib. 



Fronds perforated witli holes A(inrum. 



Fronds entire, witli lateral leatlets at the base of lamiua Ahwlu. 



Frouds destitute of midrib. 



Cryptostomata present Saccorhiza. 



Cryptostoniata wanting Laminaria. 



CnOKDA, Stack. 



(From chorda, a stritij^.) 

 Fronds olive-brown, attached by a disk, simple, cyliudrical, hollow, 

 with diaphragms at intervals ; cells of tubular portion elongated, hex- 

 agonal in section, lined on the inside with filaments, which at intervals 

 are woven together so as to form the diai^hragms; whole surfiice of 

 the frond clothed with cuueate-clavatc cells (paraphyses), which form a 

 cortical layer; unilocular sporangia ellipsoidal, situated between the 

 paraphyses, growth basal; plurilocular sporangia unknown. 



A small genus, consisting of three or four species, which are by some writers placed 

 a the Chordariacew aud by others in the Laminarlac^w. The typical species, C. JUiim, 

 may be regarded as the lowest representative of the Laminariacca;, inasmuch as it has 

 the basal uuxle of growth and the unicoUalar paraphyses of that order, but a simple 

 fioud in which there is no distinction of stipe aud lamina. Sec, also, remarks under 

 ^ ytosiplwii. 



C. FILU3I, Linn. (Scytosiphon Jilumj Ag. — Chorda Jihim^ Phyc. Brit., 

 PI. KH: Annales des Sciences, Ser. 3, Vol. XIV, PI. 20, Figs. 5-10.) 

 PI, VI, Fig. 1. 



Fronds gregarious, cartilaginous-lubricous, quarter of an inch in diam- 

 «ter, from one to twelve feet long, attenuate at base, densely clothed 

 with hyaline hairs ; paraphyses cuneate-clavate, slightly longer than tlie 

 sporangia and overlapping them. 



On stones at low-water mark and below. 



Common along the whole coast ; Europe. 



At once recognized by its cord-like appearance. The early form, which is densely 

 overed with hairs, constitutes the C. tomcntona of some writers. Areschoug, however, 



•nsiders that the true C. tomentom of Lyngbye is distinct, and characterized by its 

 longatod linear parajdiyscs, which arc scarcely as long as the sporangia, which ripen 



irly in the season, while those of C.filum ripen in the latter part of summer aud 

 lutumn. 



