226 CERAMIACE^. v. 



removed further apart by the elongation of the internodes, and the branches become 

 beaded at intervals. 



1. Ceodania attenuata, J. Ag.; frond attenuated upwards; the tetraspores 

 solitary, triangularly parted. /. Ag. Sp. Alg. %p. 105. Harv. Phyc. Brit. t. 1U6. 

 Callithamnion nodulosum, Kutz. Sp. Alg. p. 651. (Tab. XXXI. D.) 



Hab. Key West, W. H. H., 68, m ; Dr. Blodgeit, 56, 61. (v. v.) 



Fronds tufted, one to two inches long, capillary or setaceous, irregularly 

 branched ; branches lateral, alternate or secund, or sub-dichotomous, more or less 

 divided ; the lower ones mouiliform, the upper more and more cylindrical from the 

 greater closeness of the whorls of ramelli ; the apices attenuated to a fine point. 

 Colour, a dull, dark purple. 



The Key West specimens are much infested with calcareous matter and do not 

 recover well after having been dried. The magnified sketch in our figure was 



o o o 



made on the spot, from fresh specimens. 



Plate XXXI. C. Fig. 1. Crouania attenuata ; a tuft, the natural size. Fig. 2, a 

 branch ; jig. 3, one of the ramelli from the same ; fig. 4, occasionally trichotomous 

 apices of a ramellus ; the latter figures more or less highly magnified. 



VI. HALURUS. Kutz. 



Frond cartilaginous, filiform, articulated, monosiphonous, irregularly branched ; 

 branches clothed at the nodes with short, incurved, dichotomous, whorled ramuli. 

 Favellce generally several in a cluster, borne on the apex of a shortened branch, and 

 sub-tended by a whorl of involucral ramuli, containing, within a hyaline periderm, 

 numerous angular spores. Tetraspores attached to the interior side of the branches 

 of an involucre formed of dichotomous ramelli, numerous, spherical, triangularly 

 parted. 



This genus has been separated by Kiitzing from Grijithsia, with which it nearly 

 but not exactly agrees in the fructification, and from which it differs in external 

 habit. The plants of the present group have, except in colour, very much the 

 appearance externally of the Cladostephi. 



1. 'SALunvsequisetifolius, Kiitz.; frond irregularly branched, the branches directed 

 to every side ; whorled ramuli incurved, forked or dichotomous, densely set, their 



