1906] Collins, — Acrochaetium and Chantransia 195 



sessile or short pedicelled, secund or sometimes opposite. On various 

 algae, especially on Porpkyra, Maine to Conn. 



In size of filaments and spore characters like A. virgatula, but a 

 much shorter and more densely branched plant, with uniformly shorter 

 cells, and branching predominantly secund. 



Key to the Species of Chantransia. 



1. Unchanged spore persistent at base of filament. . . 2. 



1. Spore indistinguishable C. effforescens. 



2. Monoecious C. roseolwn. 



2. Dioecious. ......... 3. 



3. Cells 3-10 diam. long; descending endophytic filaments well 

 developed C. corymhijcra. 



3. Cells 2-3 diam. long; endophytic filaments only slightly devel- 

 oped. . C. Barhadeyisis, 



C. CORYMBIFERA Thurct in Le Jolis, Algues Marines de Cherbourg, 

 p. 107; Notes Algologiques, p. 16, PL V; P. B.-A., No. 1040, not 192. 

 Filaments erect and straight, about 8 n diam., slightly tapering above; 

 branches few below, more abundant above, alternate or somewhat 

 secund, virgate, not much branched, cells 3-10 diam. long; spores 

 sessile or short pediceled, near the base of the branch; cystocarjis 

 in the form of dense glomerules of naked spores, in the same situation; 

 antheridia on separate plants, in dense, short-pediceled glomerules 

 at various points on the branches. 



The original spore, 12-15 // diam. persistent at the base of the fila- 

 ment, sending down into the host a branching filament, about the size 

 of the erect filament, but more irregular and contorted; erect filaments 

 arising from this endophytic growth, but distinguished from the 

 primary filament by not possessing the spore cell. On Helmintho- 

 cladia purpurea, Southern California. 



C. Barbadensis Vickers, Ann. Sci. Nat., Series 9, Bot., Vol. I, 

 p. 60. Basal spore persistent; endophytic filament not much devel- 

 oped; erect filaments 12-14 a diam., cells 2-3 diam. long; fruit as in 

 C. corymbijera. Barbados, Guadeloupe. 



C. ROSEOLA (Crouan) Bornet, 1. c, p. XIX; Ccramium roseolum 

 Crouan in Desmazieres, Plantes Crypt, de France, No. 1040. Basal 

 spore distinct, emitting descending filaments penetrating the host, 

 and erect filaments with more or less secund branches; cystocarpic 



