44 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



species approaches Ulva clathrata. Innumerable varieties have been made of the 

 various forms of this species, but an enumeration of them is quite uncalled for in this 

 place. 



Ulva clathrata, Ag. 



" Frond tubular, filiform, several times branched, branches attenuate 

 at the apex, often very fine, cells arranged in rows." (Le Jolis, Liste 

 des Algues Marines de Cherbourg.) 



As usually defined by algologists, Ulva clathrata differs from U. compressa princi- 

 pally in the smaller size of the branches, a character by no means constant. AVe 

 quote the specific distinctions as given by Le Jolis, 1. c, which exi^ress more clearly 

 than the descriptions of other writers the relations between the si^ecies : 



'' I think they (the specific characters) are to be found, first, in the general form of 

 the fronds, which, broadened at the summit in the ditferent varieties of Ulva entero- 

 morjpha, are, on the contrary, much attenuated at the extremity in Ulva clathrata. 

 Secondly, in the ramification. While Ulva compressa and intestinalis are rather proliferous 

 than branching in the true acceptation of the word — their branches being ordinarily 

 of such a character that when they are given off from the lower part of the frond there 

 does not exist, so to speak, any principal axis, or when borne towards the extremity 

 of the frond reduced to simple proliferations; in Ulva clathrata, on the contrary, there 

 exists a well-marked ramification, the fronds or primary axes bearing numerous sec- 

 ondary branches, which in their turn produce branchlets of an inferior order." 



•Of the species, as defined by Le Jolis, there are several varieties common on our 

 coast, principally to be distinguished by the fineness of the branches and more or less 

 complicated ramification. The vshTiety Agardhiana of Le Jolis {Enter omorphaLinMana, 

 Grev. ), rather coarse and rigid, is common in shallow water, as is also the form called 

 by Harvey Enteromorpha ramulosa. The var. liothiana forma 2??'0sfmf« is found in a 

 ditch at Maiden, Mass. 



Ulya Hopktrkii, (McCalla) Harv., Phyc. Brit., PL 263. 



Frond capillary, excessively branched, ramuli ending in a siugle row 

 of cells. 



Greenport, L. 1., 3Ir. Hooper ; Gloucester, Mass., il/rs. A. L.Davis; 

 Europe. 



A beautiful species, looking much more like a fine Cladophora than an Ulva. It is in 

 most cases easily recognized by its tenuity and light-green color. It grows in large 

 tufts on other algse and is about eight or ten inches long. It is by no means certain 

 that this species should not be regarded as an extreme variety of U. clathrata in spite 

 of the fact that the branches usually end in a single row of cells. 



ULOTHRIX, (Kiitz.) Thur. 



(From vXtj, a forest, and ■&pi^, a hair.) 



Filaments grass-green, soft and flaccid, unbranched, at first forming 



tufts attached at the base, afterwards becoming more or less entangled, 



cells never long in proportion to their diameter. 



The genus Ulothrix here includes all the unbranching marine Chlorosporece of a deli- 

 cate texture, and embraces the species included by Hars^ey inthe genus Hormotrichum 

 of Klitzing, which can hardly be kept distinct from Ulothrix, an older genus of Kiitzing. 

 When young the species of the genus are attached at the base and unbranched, but in 

 some cases, when old, the filaments are twisted together, and it is not always easy to 

 find the point of attachment. 



