46 PROCEEDINGS OF THE AMERICAN ACADEMY 



V. 



CONTRIBUTIONS FROM THE CRYPTOGAMIC LABORATORY OF 



HARVARD UNIVERSITY. 



XV. — ON THE STRUCTURE AND DEVELOPMENT 

 OF CHOREOCOLAX POLYSIPHONI^, Reinsch. 



By Herbert Maule Richards. 



Presented by W. G. Farlow, May 12, 1891- 



Heretofore comparatively little has been known concerning the 

 obscure parasitic alga, Choreocolax Pohjsiphonice, Reinsch. Little 

 has been written concerning it, and, so far as I know, only one other of 

 the various forms included in the original description under the same 

 genus has been the suliject of even a note. It was with a hope of 

 addinif something new to our knowledge of it that I undertook the ex- 

 amination of this plant. The observations resulted in the discovery of 

 several interesting facts, which, together with a general description of 

 the alga are embodied in this paper. 



The literature concerning the genus Choreocolax, besides the origi- 

 nal description, consists of only a few scattered notes. The genus 

 was first described and figured by Reinsch in his " Contributiones ad 

 Alo-olofTJiim et F'unsoloQ-iara." * There he mentions several species 

 parasitic on various alga?, but described only from sterile specimen*. 

 Among them is Choreocolax Pohjsiphonice, growing on PoJysijyhonia 

 fastigiala, the only species that has been reported to have been found 

 on the American coast since Reinsch 's original descriptions. The next 

 notice of these parasites is by Farlow, in his New England Alga?,t 

 where in a foot-note he briefly mentions them. In a paper published 

 later. $ he makes mention of C. pohjsiphonicB^ descril)ing for the first 

 time the tetraspores of this plant. They develop from the terminal 

 cells of the plant, and may be either tripartite or cruciate ; usually the 



* Pase 61, Plate XLIX. 

 t Pa fie 101. 



X On some New or impcrfectl}' known Algae of tlie United States. Bull. 

 Torrey Bot. Club, Vol. XVI. No. 1, p. 6, Plate LXXXVII. 



