NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 161 



Bossea insularis varies considerably in size but little in relative pro- 

 portions. The illustrations show something of this range of size among 

 the Mexican plants, from the dwarfish ones of Punta Santa Rosalia to 

 the large form found at Bahia Asuncion and at some of the California 

 Channel Islands. 



The species is distinctive in its short, broad intergenicula, usually 

 under 3 mm. in greatest dimensions, and in its bushy habit and usually 

 dominant pinnate branching. Frequent 1-2-segment pinnae are char- 

 arteristic. Our specimens in part agree fairly well with Smith's illustra- 

 tion (1944) of Bossea corymbifera Manza, but his figure does not cor- 

 respond with Manza's type and seems to represent an undescribed entity. 

 Further study of B. corymbifera in central California is necessary before 

 the specific limits of that name can accurately be determined. In size and 

 aspect B. insularis may resemble B. plumosa Manza (including B. 

 frondifera Manza^), but it is neither so richly branched above, nor 

 provided with so many of the short, lateral pinnae which give B. plumosa 

 its characteristic feathery appearance. Some narrow examples may ap- 

 proach B. cooperi, especially in branching, but are distinct by manner of 

 the short, broad, round-lobed intergenicula. 



1 An examination of the single large collection of Bossea from Moss Beach, 

 California which includes the type specimens of Manza's B. plumosa and B. 

 frondifera has revealed that these names probably represent two variations 

 in a single population. Although superficially the holotype specimens appear 

 quite distinct, closer inspection reveals the similarity of fundamental construction. • 

 The types of B. plumosa and B. frondifera seem to exemplify two peaks of vari- 

 ability, while other examples intermediate between them, but from the same 

 collection, were not named by Manza. In other collections, such as Silva 2817, 

 Lucia, Calif., series of specimens are found which show a range of characters 

 from B. plumosa to B. frondifera, with the "plumosa" type by far the commoner. 

 The ovate leaflets of B. frondifera seem to be the result of a tardiness by the 

 pinnae in cutting off pinnulae. 



