THE MARINE ALGJ2 OF NEW ENGLAND. 85 



afterwards becoming fistulose and tubular; peripheral filaments short, 

 fevr-celled, the last cell obovate and several times larger than the other 

 cells ; unilocular sporangia ovoid. 



On algae and stones near low- water mark. 



Yery common from Cape Cod southward; Niles Beach, Gloucester, 

 Mass.; Europe. 



A characteristic species of Long Island Sound, where it is probably more abundant 

 than in any other part of the* world. It abounds in still, shallow bays. North of 

 Cape Cod it is of small size, and is only occasionally met with. It assumes a number 

 of different forms, none of which, however, can be considered as distinct varieties. It 

 first appears in May, and reaches perfection in August and September. At first the 

 fronds are small and solid, but they grow to be two feet long, or even longer, and the 

 main branches become hollow and finally collapsed. Except that they are more lux- 

 uriant, our forms agree well with Norwegian specimens. 



M. VEEivncuLAEis, Ag. j Phyc. Brit., PI. 31. 



Fronds tufted, gelatinous, one to two feet long, branches long, irregu- 

 larly pinnate, thick, vermiform, flexuous ; peripheral filaments clavate, 

 somewhat incurved, moniliform cells spheroidal ; unilocular sporangia 

 ovoid. 



On stones and algae between tide-marks. 



Halifax, N. S., Harvey ; Europe. 



A rather common plant of Europe, and probably occurring within our limits, but as 

 yet only reported at Halifax on the American coast. The species is rather thick and 

 clumsy, and very gelatinous ; not at all likely to be confounded with M. divaricata, 

 which is less gelatinous, has a different mode of branching, and whose peripheral fila- 

 ments are terminated by a cell much larger than the others. Dried specimens may be 

 mistaken for Castagnea vireseens, a more slender plant, with longer and more slender 

 peripheral filaments, the upper cells of which are transformed into- plurilocular spo- 

 rangia. We have only examined dried specimens of this species. 



CASTAGNEA, (Derb. & Sol.) Thuret, emend. 



(In honor of Louis Castagne, a French botanist.) 



Fronds and unilocular sporangia as in Mesogloia ; plurilocular spo- 

 rangia formed by outgrowths from the uppermost cells of the peripheral 

 filaments. 



C. vtkescens, (Carm.) Thuret. (Mesogloia vireseens, Carm., in Phyc. 

 Brit. ; Ner. Am. Bor., Vol. 1, PL 10 h ; Ann. Sci. Nat., Ser. 3, Vol. 14, 

 PL 27.) PL 7, Fig. 1. 



Fronds filiform, gelatinous, three inches to a foot and a half long, axis 

 clothed with numerous, irregular, flexuous branches, ultimate branches 

 short, given off at wide angles ; fronds at first solid, becoming fistu- 

 lous ; peripheral filaments slender, clustered, recurved or incurved, cyl- 

 indrical or only slightly moniliform, cells ellipsoidal, .015-20 mm in diam 

 oter; unilocular sporangia ovoid al or rhombic- ovate; plurilocular spo- 



