42 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Eastport, Maine; Gloucester, ^N'aliant, Mass.; Xortlieiu Europe. Au- 

 tumn. 



This, by far the most striking of our Monostromata, grows hixiiriautly iu the large 

 tide-pool at Dog Island, Eostport, where it attains a length of ooe foot. In habit it 

 resembles Ulva lactuca var. rigida, bnt it is of a deeper green. Onr specimens were 

 collected in the month of September. As it occnrs at Nahant the species is not gen- 

 erally more than two or three inches long, and recalls the fignre of VUa ohscura, Kiitz., 

 Tab. Pbyc, PL 12, No. 2. It is found in the clefts of exposed rocks, late in the season. 

 Its color is a deep green when growing, which becomes brownish in drj'ing. It does 

 not adhere well to paper. 



M. CREPIDINUM, n. sp. 



Fronds delicate, liglit green, one to three inches long, flabellately or- 

 biculate, split to the base, segments ohovate, .018-36™°^ thick, cells 

 roundish-angular, intercellular substance prominent. 



Government wharf. Wood's HoU, Mass. August. 



This small species is common on the piles of the wharf at Wood's Holl. It is very 

 soft, and collapses on removing it from the water. It preserves its color well on paper. 

 The above name is given provisionallj^, as we are not able to refer the species to any 

 known form. It resembles M. WittrocJcii, Bornet, a species, we believe, not yet de- 

 scribed. Except in its small size, it is very near M. orbicuJatum, Thnr., but the thick- 

 ness of that species, as given by Wittrock, is .032-40'"'". An examination of a specimen 

 collected by Thuret, however, gives the same measurement as our species. If the 

 species eventually is united with M. orhiculatum, the present must be regarded as a 

 small form. 



ULVA, (L.) Le Jolis. 



(Supposed to be from ul, Celtic for water.) 



Fronds simple or branching, consisting of two layers of cells, which 

 are either in close contact with one another or else at maturity separate 

 so as to form a tubular frond. 



We have followed Le Jolis in uniting the old genera Ulva and Enteromorpha, and we 

 might perhai^s have gone farther and united Monosiroma with Ulva, for if Monostroma 

 Grevillei when young resembles an Enteromorpha, in its older stages it splits into 

 membranes consisting of a single layer of cells, which are certainly imbedded in a cer- 

 tain amount of gelatinous substance, yet so little as to make it doubtful whether to 

 call the frond parenchymatous or not. 



U. Lactuca, (Linn.) Le Jolis. ( TJlva Jatissima and rigida^ Ag. & Auct. 

 recent. — JJ. latissima, Grev. & Harv. — Phycoseris gigantea, myriotrema^ 

 austraUs, &c., Klitz.) PL III. Fig. 1. 



Frond flat, thick, unbranched, variously more or less ovate in outline, 

 divided, the two layers of cells adherent. 



a. Yar. RIGIDA, (Ag.) Le Jolis. {JJ. rigida^ Ag.— V. latissima^ Harv., 

 Phyc. Brit., partim. — Phycoseris australis, Klitz.) 



Frond rigid, rather thick, generally deeply divided, lacini^e irregu- 

 larly lacerate-erose, the base of frond more dense and deeply colored 

 than the rest. 



