THE MARINE ALG.E OF NEW ENGLAND. 175 



Var. fucoides, Ag. ; Phyc. Brit., PL 277. 



Fronds robust and naked below, upper branches pectinate or corym- 

 bose, articulations but slightly longer than broad. 



Var. affinis, Ag. ; Phyc. Brit., PL 303. 



Fronds elongated, diffusely branching, branches distant, undivided 

 below, densely pinnate at the tip, articulations two or three times as 

 long as broad. 



In tide-pools and below low- water mark on stones and alga>. 



Common along the whole coast. 



One of our commonest and least beautiful species, which, although very variable, is 

 generally easily recognized. In the Nereis, Harvey describes seven forms found on 

 our eastern coast. Practically, the species as found with us is recognized under two 

 principal forms. The first is rather robust, and has branches which are more or less 

 pectinate or corymbose, and in the extreme forms, as var. Durkeei, Harv., 1. c, PI. 17 c, 

 they are compressed, and the pinna} are distichous and abbreviated. The second form 

 of the species is represented by the P. affinis of the Phycologia Britannica, in which 

 the main brancbes are much elongated and more delicate than in var. fucoides, and the 

 ultimate divisions are arranged in pyramidal tufts. Between the two types described 

 occur innumerable forms which hardly require a further description. 



P. fastigiata, Grev. ; Phyc. Brit., PL 299. 



Fronds dark brown, forming globose tufts one to three inches in 

 diameter, filaments rigid, of nearly the same diameter throughout, re- 

 peatedly dichotomous, fastigiate, apices subulate, spreading, occasion- 

 ally forcipate, siphons averaging about 20, articulations decidedly broader 

 than long; antheridia oval, in dense terminal tufts; cystocarps ovate, 

 taking the place of a terminal dichotomy. 



On Ascopliyllum nodosum. 



Common from New York northward ; Europe. 



A very common species, at once recognized by its form and place of growth. It 

 forms tufts on Fucus (AscophyUum) nodosus and, according to Harvey, on F. vesiculosus. 

 Its color is so dark that one at first sight would hardly suppose it to be one of the 

 Flovidece. The filaments are rigid, and the plant does not collapse in the least when 

 removed from the water, nor does it adhere to paper in drying. The antberidia 

 are very abundant early in the season. Tbe species, like most of the genus found on 

 our coast, is dioecious, but occasionally one finds both sexes on the same individual. 

 In this connection, it would be well to inquire if there is not a proterandrous condi- 

 tion among the Floridece, as in the higher plants. It has seemed to us that such a 

 condition may exist in P. rariegata, and possibly in the present species. P. fastigiata 

 is said to have been collected in California, but the locality is doubtful. It has been 

 found also in Australia and New Zealand. 



BOSTRYCHIA, Mont. 



(From fioorpvxLov, a small curl.) 

 Fronds dark purple, compressed or filiform, distichously or irregu- 

 larly branching, composed of several (4-11) cells (siphons) arranged 

 around a central filament, the siphons either naked or corticated with 

 subcubical cells, apices usually monosiphonous ; tetraspores tripartite, 



