150 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



RHODYMENIxi, (Grev.) J. Ag. 

 (From podeog, red, and v/j}]v, a membrane.) 



Fronds flat, membranaceous, dicliotomons or palmate, composed of 

 an internal layer of large roundish-angular cells and a cortical layer of 

 smaller cells, in some cases arranged in short horizontal filaments; 

 tetraspores cruciate, either collected in superficial spots (sori) or scat- 

 tered in the cortex; cystocarps external, sessile, with a distinct car- 

 postome, spores irregularly grouped in masses attached to a basal pla- 

 centa and surrounded by a gelatinous envelope. 



A geuus whicli formerly was made to include a large number of flat membranous 

 species, a large part of whicli have by recent writers been removed to other genera. 

 We have but one species on our coast, Rliodymema palmata, the common dulse, of which, 

 unfortunately, the cystocarpic fruit is unknown, and the study of the fruit of the 

 genus is out of the question with us. 



R. PAL3IATA, (Linn.) Grev. ; Phyc. Brit., Pis. 217, 218; Ann. Sci. l!Tat., 

 Vol. Ill, Ser. 4, PI. 3, Pig. S.— Dulse. 



Pronds purplish red, broadly wedge-shaped, six to twelve inches long 

 and four to eight inches broad, irregularly cleft, palmate or dichoto- 

 mous, sometimes repeatedly laciniate, the margin often winged with 

 leaflets ; tetraspores cruciate, scattered in i)atches over the frond, im- 

 mersed in the cortex ; cystocarps ? 



Yar. Sarniensis. 



Divisions very numerous, narrow, sublinear. 



On Fuel, LaminaruVj and other algce, between tide-marks, and extend- 

 ing into deep water. 



Common from I^ew York northward ; Korth Atlantic ; California? 



This, with Chondrus crispus, forms the only species eaten in New England. The present 

 species, although one of the commonest red sea-weeds in the North Atlantic, has never 

 been known to bear cystocarps, and hence the generic position is doubtful. The 

 description given applies to the typical form, and although the fronds are very variable 

 in outline, the species is easily recognized. It is sold in the seaport towns, where it 

 is to be found dried on the fruit-stands of the women who sell green apples, corn-balls, 

 and other dainties. It is said to possess anthelmintic properties, which, if one can 

 judge by its disagreeable taste, is very j)robable. 



PLOCAMIUM, Lyngb. 



(From 'rrloKuixog, a lock of hair.) 



Fronds compressed, membranaceous, pinnately decompound, the pin- 

 nules alternately secund in twos, threes, fours, or fives, composed of an 

 inner layer of longitudinal, oblong cells and a cortical layer of smaller ^ 

 polygonal cells ; tetraspores zonate borne in special branchlets ; cysto- 



