86 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



rangia siliciilose, comx^osed of three to six cells, formed from the terminal 

 cells of i^eripheral filaments, often secund on the upper side. 



On sand-covered rocks and algse at and below low-water mark. 



Wood's Holl, Nahant, Gloucester, Mass. ; Portland, Maine, Mr. Fuller; 

 Europe. 



A species which is rather cornmou in the spring months, bnt which disappears with 

 lis about the 1st of July. The fronds are more slender than in M. vermicularis, but 

 when dried under too great pressure, or when allowed to remain some time in fresh 

 water, they somewhat resemble that species. The distinction is best seen in the periph- 

 eral filaments. Those of M. vermicularis are shorter, decidedly clavate, less curved, 

 and are formed of spheroidal cells. In C virescens they are longer, more nearly cylin- 

 drical, recurved, and formed of ellii^soidal cells. The number and size of the pluri- 

 locular si^orangia vary very much. 



O. Zosters, (Mohr.) Thuret. {2Ii/riocla(Ua zostercVj Ag. — 2Iesogloia 

 vermicularis^ var. zosterw, Kiitz., Spec. Alg. — M. virescens^ var. zosteri- 

 cola, Harv., Phyc. Brit., PL 82. — 21. zostercVj Aresch., in Ner. Am. Bor., 

 Yol. I, p. 127, PI. 10 a.) PL 7, Fig. 2. 



Fronds filiform, gelatinous, three to eight inches long, subsimple, fur- 

 nished with a few short, remote branches, given off at wide angles j 

 I)eripheral filaments erect, rather rigid, cylindrical below, moniliform 

 above J cells spheroidal, .02-4^"°^ in diameter j unilocular sporangia ovate; 

 plurilocular sporangia siliculose, composed of three to six cells, usually 

 forming dense tufts on the upper part of the peripheral filaments. 



On eeLgrass. 



Wood's Holl, Gloucester, Mass. ; Europe. 



A small species with very few branches, which, although it has been by some con- 

 sidered a variety of C. virescens, is sufficiently distinct both in its microscoj)ic structure 

 and the season of growth. C. virescens is a spring form, which disappears in early 

 summer, while C. Zoster(e, at least on our coast, occurs in summer and autumn. The 

 appearance of the peripheral filaments is different in the two species. In C. virescens 

 they are slender and curved and in C. zosterce rather stout and erect and more densely 

 packed together, in this respect resembling M. vermicularis, in which, however, the 

 filaments are distinctly clavate and moniliform, and do not produce plurilocular spo- 

 rangia at the extremity. A section of the frond of a well-developed C. virescens shows 

 a circle of roundish cells around a central cavity and on the outside a series of branch- 

 ing filaments, which end in the proper peripheral filaments and sporangia. In C. Zos- 

 terce there is also a circle of cells surrounding a central cavity, but the peripheral fila- 

 ments seem to be given off directly from the circle of cells. The figure in the Nereis 

 Am. Bor. does not correctly represent the structure of C. Zosterce, for the clusters of 

 peripheral filaments are not outgrowths from special colored filaments, but from the 

 uncolorod cells. American specimens agree perfectly with the specimens of Mesogloia 

 zosterce, No. 100, of Areschoug's Alg. Scand. 



Family EALFSIEiE. 



Fronds horizontally expanded, sometimes crustaceous j fructification 

 in raised spots (sori), composed of few-celled club-shaped paraphyses 

 and spheroidal unilocular sporangia. 



