136 HELMINTHOCLADE^ v. 



c'late, always regular in its ramification, but very variable in size and in substance. 

 The widest specimens are always the most delicately membranaceous and gelatinous, 

 the narrower ones being much firmer and of darker colour. The branches are 

 ba"--like, and filled with a half slimy, half watery gelatine, which may be squeezed 

 from them, and which, being exuded in drying, causes the filmy remains of the 

 plant to adhere very strongly to paper. The aa;is is composed of a densely inter- 

 woven rope -like bundle of very slender, longitudinal filaments, and is much more 

 strongly developed in some specimens than in others ; sometimes being reduced to 

 a few threads, sometimes of considerable diameter, appearing in the dried plant 

 like a strong midrib, A considerable space, filled with gelatine, intervenes between 

 this axis and the membranous periphery, which is, however, organically connected 

 with the axis throughout by innumerable obliquely-horizontal dichotomous filaments, 

 or branches issuing from the axial threads, and terminating in the periphery. 

 These constitute the intermediate stratum of the frond. The periphery is composed 

 of one or two rows of roundish, coloured cellules, as it were the apices of the 

 excurrent filaments of the axis, united together into a membrane. 



The sporiferous nuclei, which are almost always to be found, are abundantly pro- 

 duced in all parts of the frond. They are suspended immediately within the 

 membranous walls, or among the upper dichotomies of the excurrent, horizontal 

 filaments. Professor Agardh describes them as naked, and as such I formerly 

 figured them in Phycologia Britannica ; but a recent examination, carefully made 

 with a high magnifying power, fiivours the existence of a thin, membranous peri- 

 carp, composed of hexagonal cells, as described by Dr. Montagne. On removing 

 some nuclei and pressing them gently between two pieces of glass, I repeatedly 

 have seen a thin torn membrane among the dispersed sporethreads, and which most 

 probably invested the ball. I have not, however, been able, by any other means, 

 to obtain a view of it. 



I follow Professor Agardh in adopting the name Scinaia, proposed, it would 

 appear, so long ago as 1822, though overlooked until recently. I regret being 

 obliged to lay aside that of Ginannia, under which the genus has been generally 

 adopted, but the stringent laws of priority allow me no choice. 



1. ScmkiA furcellata, Bivona ; frond cylindrical, tender, uniformly dichotomous, 

 fastigiate, equal or here and there constricted ; apices obtuse. J. Ag. Sp. Alg. vol. 

 2, JO. 422. Ginannia furcellata, Mont. — Ilarv. Phjc. Brit. t. 69- Kutz. Sp. Alg. p. 715. 

 Myelomium furcellatum, Kutz. Phyc. Gen. t. 73,/. 1. Ulva furcellata, E. Bot.t. 1881. 



Hab. Newport, Rhode Island, Prof. Bailey. Key West, W. H. H. (v. v.) 



Frond two to four inches long or more, cylindrical, varying much in diameter, 

 sometimes as thick as a swan's quill and sometimes not thicker than a sparrow's 

 quill, many times forked, regularly dichotomous, level-topped, the branches when 

 displayed having a definite, semicircular outline. Lower dichotomies sub-distant, 

 upper successivel}^ closer together. Axils and apices blunt. Substance more or less 



