THE MARINE ALG.E OF NEW ENGLAND. 63 



SCYTOSIPHON, (Ag.) Tlmret. 

 (From gkvtoc, a whip, and cwpuv, a tube.) 



Fronds simple, cylindrical, usually constricted at intervals, hollow, 

 cortex of small colored cells, inner layer of vertically elongated, color- 

 less cells ; sporangia as in Pliyllitis ; paraphyses single-celled, oblong- 

 obovate, interspersed among the sporangia. 



The present genus is founded on the Chorda lomentaria of older writers. The genus 

 Scytosiphon, as proposed by Agardh, included both C. lomentaria and C. filum. The 

 latter species, which is still kept in the genus Chorda by most writers, has the surface 

 of the frond covered with club-shaped paraphyses, between which are situated the 

 oral unilocular sporangia. In S. lomentarius the bodies called paraphyses are only oc- 

 casionally found, and their real nature is a little uncertain. Both Bornet and Ares- 

 choug consider them to be paraphyses, and the latter has figured them in Observa- 

 tiones Phycologicse, Part III, PI. 2, Fig. 1. As at present understood, Scytosiphon differs 

 from Pliyllitis only in the fact that the frond is tubular instead of membranous, and in 

 the presence of paraphyses, which have not yet been found in Phyllitis. 



S. lomentakius, Ag. (Chorda lomentaria, Lyn'gb.; Phyc. Brit., PI. 

 285. — Chorda filum var. lomentaria, Kiitz., Spec. Alg.) 



Fronds gregarious, three to eighteen inches long, attached by a disk- 

 like base, shortly stipitate, expanding into a hollow tube, from a quarter 

 of an inch to an inch in diameter, at first cylindrical, afterwards con- 

 stricted at intervals. 



Very common on stones between tide-marks; found nearly all over 

 the world. 



A species easily recognized, except when quite young, by its tubular and constricted 

 frond, but chiefly interesting in consequence of the smaller species of alga3 which grow 

 upon it. At Eastport a very large form is found, nearly an inch in diameter, and 

 much twisted. 



Family PUNCTARIE^. 



Fronds unbranching, forming expanded membranes or cylinders; 

 fructification in spots (sori) on the surface of the fronds ; plurilocular 

 sporangia ellipsoidal, composed of few cells ; unilocular sporangia sphe- 

 roidal. 



PUNCTARIA, Grev. 



(From punct urn, a point, referring to the dots formed by the sporangia and hairs.) 



Fronds olive-brown, simple, membranaceous, attached by a discoidal 

 base, composed of several (2-6) layers of cuboidal cells of about the same 

 dimensions in all parts of the fronds ; unilocular sporangia immersed 

 in the frond, collected in spots, spherical-cuboid, formed from the su- 

 perficial cells; plurilocular sporangia collected in spots, immersed ex- 



