158 University of California Puhlioations in Botany [Vol. 8 



proportions of the piunules and, especially, the shape of the bases 

 of the older pinnules, as important characters. The bases of branches 

 and branchlets, especially below on the main or secondary axes, may 

 produce rhizoid-like, almost corticating, structures, and these seem to 

 present differences, possibly of diagnostic value. M. A. Howe has 

 particularly called attention to this in his "Marine Algae of Peru" 

 (1914, p. 38 et seq. and pi. 7, f. 6-9). They were also made part 

 of the distinction in B. corticulans Setchell, but they exist in many, 

 or possibly all, species, varying in their shape and distribution. 



Key to the Species 



1. Thallus small, more or less simple 1. B. pennatula (p. 158) 



1. Thallus 8-14 cm. high, much branched 2 



2. Pinnules arising on all sides of the branches 2. B. hypnoides (p. 159) 



2. Pinnules distichous 3 



3. Base of pinnules abruptly constricted and unequally rounded 



3. B. corticulans (p. 160) 



3. Base of pinnules gradually tapering and not appreciably rounded 



4. B. plumosa (p. 161) 



1. Bryopsis pennatula J. Ag. 



Thallus more or less simple, sublinear in outline, distichously 

 pinnate ; pinnules nearly equally long, cylindrical, obtuse. 



Known only from the type locality ' ' St. Augustin, ' ' on the Pacific 

 coast of Mexico, where it was collected by Professor Liebmann of 

 Copenhagen. 



J. G. Agardh, Nj^a alger fran Mexico ("Algae Liebmannianae"), 

 1847, p. 6 ; Kuetzing, Spec. Alg., 1849, p. 492, Tab. Phyc. vol. 6, 1856, 

 p. 27, pi. 76, f. II. Bryopsis pennata var. minor J. G. Agardh. Till 

 Alg. Syst., 1886, part 5, p. 23. Bryopsis pennata Collins, Green Alg. 

 N. A., 1909, p. 405 (in part). 



The only information available concerning this species is derived 

 from Agardh 's description and Kuetzing 's figure. The latter seems 

 to have been drawn from a specimen of the type collection. Agardh, 

 later, as may be seen from the references above, reduced this species 

 to a form of Bryopsis pennata Lamour. Comparing figures and speci- 

 mens of B. pennata, there seems to be a close resemblance in habit and 

 even in the shape of the pinnules, but the Mexican plant is very small 

 and slender, as compared with typical B. pennata, and it seems best 

 to us to keep it distinct until additional collections throw further light 



