HOWK : PmYCOLOGICAL STUDIES 99 



thicker (0.4-O.6 7'S. 0.09-0. 16 mm.), more rigid, less zonatc 

 flabcllum and its subcuneate base, by the larger (46-84 // ts. 8- 

 30//), less flattened filaments, which are regularly and strongly 

 constricted above the dichotomies, and by the character of their 

 lateral appendages, which arc closely 1-3 times dichotomous in- 

 stead of simple or once furcate and are 55-160 /^ long instead of 

 11-30//, long, the spines crowning a thick stump-like base or 

 pedestal instead of being practically sessile. 



From Udotea argentea Zanard., judging by the original descrip- 

 tion and figures, by a description recently published by A. & K. 

 S. Gepp,* and by American plants which we are somewhat doubt- 

 fully identifying with that species, U. spimilosa differs in its much 

 thicker, more rigid, less zonate flabellum, which is 3-7- instead of 

 I- or 2-stratose, in the filaments being constricted above the dichot- 

 omies, in their spine-like instead of obtuse, truncate, or capitate 

 appendages, which are secund instead of commonly protruding in 

 all directions, and in the taper-pointed instead of truncate or 

 obtu.se ultimate divisions of the stipe-cortex. 



From Udotea conglutinata, U. spinnlosa differs greatly in the 

 presence of appendages on the filaments of the flabellum and in 

 the calcareous sheaths of the filaments being non-porose. 



From Udotea Flabellum, with its strongly marked zonations and 

 highly differentiated cortex, the present species is so widely differ- 

 ent that comparison is unnecessary, 



* Trans. Linn. Soc. Bot. II. 7 : 176. 1908. 



