MARINE ALGM OF BEAUFORT, N. C. 433 



The species is distinguished from C. decorticatum by its more rounded, more densely branched 

 thallus, and sometimes by its smaller utricles. The extremes of these species are very different in 

 appearance, but they are connected by numerous intermediate forms so that it is often very difficult to 

 decide to which species a given specimen should be referred, especially since the utricles may vary 

 greatly in size, and the thallus is always more or less flattened belowthe dichotomies. 



2. Codium decorticatum (Woodward) M. A. Howe. PI. LXXXV, fig. 2. 



Ulva decorticala. Woodward, 1797, p. 55. 

 Codium elongatum, Agardh, 1822, p. 454. 

 Codium elongatum, De Toni, 1889, p. 496. 

 Codium elongatum, Collins, 1909, p. 388. 

 Codium decorticatum, Howe, 1911, p. 494. 

 Codium decorticatum, Collins, 1912, p. 99. 

 P. B.-A. Nos. 627 (C. elongatum), 2017. 



Frond dichotomo'usly branched, often much elongate, younger divisions terete, older ones flattened, 

 especially below the dichotomies, being there distinctly cuneate; utricles obovate-clavate, 300 to 400 

 mic. in diameter(?), five to six times as long as the greatest diameter. 



North Carolina to Florida; West Indies; Lower California, Mexico; South America; Europe; Africa. 



Beaufort, N. C.: Abundant on Bogue Beach after winds; occasional in Beaufort Harbor in earlier 

 years, becoming more abundant in later years; abundant on rocks of Fort Macon jetties, July, 1909; and 

 very abundant in harbor off Duncan breakwater and north of laboratory, September, 1909. Pawleys 

 Island, near Georgetown, S. C.: Abundant in bay near inlet, August, 1909. 



This is the northern limit of the species reported for North America. 



The species is distinguished from C. tomentosum by the greater flattening, the more elongate, less 

 densely branched frond, and sometimes by the larger utricles. The younger plants resemble C. tomen- 

 tosum, but the flattening is marked in older plants; in some cases all parts except the younger tips are 

 quite broadly cuneate. As, however, all plants of both species are more or less flattened below the 

 dichotomies, and numerous intermediate forms are found, it is often difficult to determine on this basis 

 to which species a given specimen should be referred. One specimen found at Beaufort had three main 

 divisions, two of which were flattened like C. decorticatum, while the third resembled C. tomentosum. 

 Dried specimens are particularly unreliable in this respect, since in these the amount of flattening may 

 be largely due to the amount of pressure to which the plants were subjected during drying. 



The size of the utricles furnished no criterion for distinguishing the plants of this region. While 

 those on the coarsest, widest specimens are wider, those on other individuals having the form of C, decor- 

 ticatum are narrower than many of those on individuals having the typical form of C. tomentosum. 



If the two extreme forms found at Beaufort grade into each other in other localities as much as they 

 do at this place, it may be questioned whether the present species is not merely a large form of C. tomen- 

 tosum. On the other hand, however, the fact that it was first found at Beaufort on Bogue Beach and 

 only in later years made its appearance in the harbor, indicates that it is a distinct species and that it 

 established itself in this region during the period of this study. It seems, too, to appear here later in 

 the spring and to disappear earlier in the fall than C. tomentosum. On this basis the intermediate forms 

 may possibly be ascribed to hybridization. 



This species may grow to a large size. One specimen collected on a jetty at Fort Macon had a length 

 of i meter and a width of 5 cm. below its widest dichotomy. 



Genus 2. Udotea Lamouroux. 

 Udotea, Lamouroux, 1812, p. 186. 



Frond arising from a mass of rhizoids, differentiated into stipe and flabellum ; stipe 

 erect, with distinct cortex, terminating in a fan-shaped, more or less distinctly zonate 

 flabellum, consisting of continuous, branching filaments, with more or less numerous 

 short branches attached to each other by short processes and sometimes developing 

 laterally into a more or less definite cortex; calcification more or less complete; repro- 

 duction unknown. 



