170 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



cell. The peripheral cells are similar to one another and of the same length as the 

 central cell, and, as the successive secondary cells lie exactly or nearly exactly over 

 one another, the mature frond appears to be composed of a central filament or axia 

 surrounded by a number of secondary filaments or siphons, as they are termed in speak- 

 ing of the present genus and its allies. There is formed in some species a second set 

 of cells alternating with the siphons, and also corticating, generally irregularly sinuous 

 cells, which cover the surface. The tetraspores, according to Prof. E. P. Wright, are 

 formed by out-growths from the axial cell. The antheridia are borne on the delicate, 

 colorless filaments which form tufts on the younger parts of the frond. The filaments are 

 dichotomous and the antheridia cover the lower cells of one of the forkings, the branch 

 sometimes being prolonged beyond, when the antheridia are said to be mucronate. 

 The cystocarps are terminal on short branches, and contain within a pericarp, whose 

 cells are arranged in longitudinal series, pyriform spores on short stalks around a small 

 basal placenta. Some of our species are not well defined, and a prolonged observation 

 on the shore, especially during the spring months, is necessary before the limits of 

 some species can be accurately fixed. 



Sect. I. Siphons four, cortications wanting. 



P. urceolata, (Dillw.) Grev.; Phyc. Brit, PI. 167. 



Fronds deep red, becoming blackish, caespitose, three to ten inches 

 high, setaceous, branches subdichotoinous, with short, alternate, patent 

 or recurved, decompound branchlets, siphons four, cells below 4-5 

 times longer than broad, becoming shorter above ; cystocarps on short 

 lateral branches, urceolate, with a distinct neck; antheridia linear- 

 oblong, mucronate. 



Yar. Formosa, Ag. (Polysiphonia formosa, Phyc. Brit.) 



Filaments soft and flaccid, branches long, flexuous, branchlets some- 

 what attenuated, cells 5-10 times as long as broad. 



Var. patens, Grev. (P. subcontorta, Peck, Twenty-third Eeport New 

 York State Botanist.) 



Branches numerous, recurved or revolute. 



On wharves and rocks at low-water mark. 



From New Jersey northward ; Europe ; California. 



A common perennial species, most abundant in the spring, when it has a deep blood- 

 red color. It is frequent on old wharves and wood-work and on the under surface of 

 rocks near low- water mark, where it forms small tnrfs, in company with Callithamnion 

 Bothii. The var. formosa is found only in the spring, and is softer, forms longer 

 tufts, and has longer cells than the type. It is the only form of the species which 

 adheres well to paper or which can lay claim to beauty. It is especially luxuriant in 

 April at Wood's Holl and the region of New Bedford, and forms dense tufts sometimes 

 a foot long. As usually seen in summer, the species is blackish and setaceous and 

 covered with diatomes. The var. patens, which differs somewhat in general habit from 

 the type, is not uncommon with us. Through the kindness of Mr. Peck, we have been 

 able to examine a specimen of his P. subcontorta, which, judging from the description 

 in the Twenty-third Report, seemed to be closely related to, if not a form of, P. Har- 

 veyi. An examination of the specimen, however, seems to us to show that it is var. 

 patens of the present species, which it resembles in microscopic characters. 



P. SUBTILISSIMA, Mont. 



Filaments densely tufted, two to four inches long, purplish brown, 



