HowWE: PHYCOLOGICAL STUDIES 491 
are rather difficult to distinguish from Enteromorpha compressa 
forma simplex Wittr. & Nordst. (Alg. Exsicc. 326), but the two 
layers of the thallus appear to separate less easily in the upper 
broader parts, the marginal cells in a cross section are more 
elongate and more radiately disposed, and the cells in general are 
more distinctly in lines in the lower parts. No trace of branching 
has been observed. 
Cladophora MacDougalii sp. nov. 
Rather stout, coarse, and rigid, in strict tufts, dark- or yellow- 
ish-green, 10-17 cm. high; main filaments 135-310 in diameter, 
sparingly dichotomous below the middle of the tufts; branching 
in median and upper parts lateral, the branches erecto-patent, 
secund, occasionally alternate, or very rarely opposite, becoming 
more or less secund-pectinate toward apices, the main axes com- 
monly excurrent beyond the last lateral branch as rather rigid 
tapering prolongations 10-40 cells long; the ultimate lateral 
branchlets 75-110u in diameter, about one half the diameter of 
the filaments from which they spring, usually 3-7 cells long, in 
most cases gradually tapering from near the base, subacute or 
blunt, commonly rather rigid; cells in extreme basal parts 6-15 
times as long as broad, in median and upper parts 1-4 (mostly 
114-214) times as long as broad, usually a little constricted at the 
septa and appearing quite strongly constricted when dry. [PLATE 
33, FIGURE 7.] 
San Felipe Bay, D. T. MacDougal, Feb. 1904. 
The present species is evidently allied to both Cladophora 
Hutchinsiae (Dillw.) Kiitz. and to C. ovoidea Kiitzing, but is not 
satisfactorily identified with either. In size it resembles C. 
Hutchinsiae (type from Ireland), but it is more rigid and much 
more strict in habit of growth; dichotomies are rare above the 
middle of the tuft, while in C. Hutchinsiae they commonly persist 
almost to the apices; the ultimate lateral branchlets in C. Mac- 
Dougalit are much more slender than the axes from which they 
arise, having usually, in their middle parts at least, only half the 
diameter of the parent filament, while in C. Hutchinsiae the corre- 
sponding branchlets are as a rule only slightly less stout than the 
filament from which they spring; in C. MacDougalii ultimate lateral 
branchlets of 1 or 2 cells in length are extremely rare, 5 to 7 cells 
being the prevailing number, while in C. Hutchinsiae branchlets 
of 1 or 2 cells are very common. 
