RIIODOMELACEiE. 59 



X. DASYA. Ag. 



Frond filiform or compressed, branching, opaque or rarely articulated, having a 

 polysiphonous, articulate axis, coated externally with accessory cells. Branches 

 beset with, or resolved at their ends into slender, single-tubed, confervoid, articu- 

 late ramelli. Conceptades ovate, acuminate, sessile or pedicellate, affixed to the 

 compound branches, and containing a tuft of pear-shaped spores. Tetraspores in 

 lanceolate stichidia (or transversely banded, pod-like receptacles) formed on the 

 confervoid ramelli. 



A large and considerably diversified genus, occurring in both hemispheres. As 

 here understood, it is chiefly characterised by the confervoid, jointed ramelli, issu- 

 ing from a compound, polysiphonous, but mostly opaque and outwardly inarticulate 

 frond ; and the lanceolate, pod-like receptacles of tetraspores, borne by the 

 confervoid ramelli, out of whose branches they are formed. The ramelli are of 

 the same structure as the articulated fibres which clothe the ends of the young 

 branches in Folysiphonia, Bhodomela, etc. but in those genera they are mostly 

 colourless, very fugacious, and have no connection with the tetrasporic fructifica- 

 tion ; in Dasya, on the contrary, they are persistent, containing coloured cells^ 

 and finally originating the tetrasporic fructification. In the former cases they 

 accompany the early development of the branches only, in the latter they are 

 characteristic of the species at all ages. In Bostrychia the stichidia are borne by 

 the compound branches, and in Polysiphonia the tetraspores are dispersed through 

 slightly modified and distorted polysiphonous ramuli. 



In the Nereis Australis (p. 58) I have grouped the species under five subgenera, 

 four of which are represented on the North American coasts: viz. 



Subgenus 1. *Compsoteia. — Frond more or less distinctly articulated, especially 

 in the upper branches, decompound-pinnate, distichous ; the lesser branches dicho- 

 tomous, resolved at the apices into dichotomo-multitid, confervoid ramelli. 



1. Dasya (Cojiposteia) Gibbesii ; stem compressed, areolate, inarticulate, with 

 a central line of short, transverse striae (nodes of the axial tube), distichously 

 branched, decompound-pinnate ; branches bi-tripinnate, with an obovate outline ; 

 pinnules subarticulate, dichotomous, their terminal divisions resolved into dichoto- 

 mous, single-tubed, fastigiate, confervoid ramelli ; articulations of the ramelli twicr 



* This subgenus (misspelled Campsotela) is strangely misunderstood by Kiitzing in bis " Species Alga- 

 nun," p. 797 — only two out of the fifteen species which he enumerates agreeing with the character. 

 His first species is a CatUlhamnion ; his 3rd, 5th, lOlh, are Rhodonemata ; his 9th a Wrangdia ; his 

 llth, a. Stichoearpm ; I2th, a, Lophothalia ; and 14th and 15th, Bostri/chia. The name given to this 

 uncombed assemblage is Eupogonium. 



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