138 HELMINTHOCLADE^. v. 



reefs and islands. Of the described species four or five occur in tlie Mediterranean, 

 .•md one extends along the Atlantic coast of Europe as far north as Brest, the 

 liighest latitude attained by the genus. Probably many remain to be described, 

 but require careful attention in a living state for their correct determination, as all 

 change considerably, and some can scarcely be recognized in a dried state. Several 

 reputed Galaxaurce of the section Microthoe, perhaps all the species of that section, 

 appear to me to belong to Liagora, but I have not had good opportunities of exa- 

 mining them. 



'& 



* Fronds covered with a continuous calcareous deposit. 



1. lAKGORkvalida ; frond robust, repeatedly dichotomous, fastigiate, with rounded 

 axils, becoming when dry whitish with red-ljrown apices, covered with a thin con- 

 tinuous, calcareous deposit ; apices obtuse, not attenuated ; filaments of the peri- 

 phery repeatedly forked, fastigiate, moniliform, their cells elliptical. (Tab. XXXI. 

 A.) 



Hab. Sand Key, Florida, W.H.H. (v. v.) 



Fronds tufted, two to three inches long, half a line in diameter, terete when 

 fresh, becoming compressed in drying, repeatedly and nearly regularly dichotomous 

 from the base, the axils rounded, the apices obtuse and divaricating, not at all 

 attenuate. Calcareous coat thin, but uniformly spread, completely coating the 

 peripheric filaments in the lower part of the frond, less dense near the ends of the 

 branches, allowing the tips to project beyond it. When dry, the coated portion of 

 the frond assumes a clialky whiteness. On removing the lime by acid, the peri- 

 pheric stratum resembles that of Helininthora. The periplieric filaments are three 

 or four times divided, tlie articulations of equal diameter throughout, the lower 

 ones sub-cylindrical, the upper successively more elliptical and contracted at the 

 dissepiments. The colour when recent is a pale pinky red, which is partially 

 retained in the microscopic view of the re-moistened plant. 



This may have been previously described as a Galaxaura of the section Microthoe, 

 but I am not possessed of materials sufficient to decide the point. 



Plate XXXI. A. Fig. 1. Liagora valida, tJie natural size. Fig. 2, portion of a 

 branch from which the lime has been removed ^fig. 3, axial and peripheric filaments ; 

 fig. 4, a peripheric filament ; fig. 5, apex of the same ; the latter figures more or 

 less magnified. 



2. Liagora pinnata ; stem sub-simple, closely set throughout with lateral 

 branches, which spread toward every side ; branches pinnate, or sub-bipinnate, the 

 pinna} frequently opposite, the pinnules irregularly placed, cylindrical, obtuse, 

 spreading ; calcareous deposit thin, continuous ; apices reddish-browi when dry ; 

 filaments of the periphery not much branched, irregularly dichotomous, fastigiate, 

 not beaded, their cells about twice as long as broad, cylindrical. (Tab. XXXI. B. j 



