HYDEOIDA. 123 



Lytocarpus (?) hornelli, n. sp. Plate III., %s. 1 t<> In. 



Trophosome. Colony slender, 16 inches to 18 inches in height, with long, straggling 

 branched stems (fig. 1). Stem and branches polysiphonic, of the same thickness, and 

 dark brown colour. Branches alternate usually, but occasionally several given off 

 near together and from one side of a stem. Branchlets carrying hydrocladia about 

 j l of an inch in length, arranged in loose, bottle-brush form on the branches, having 

 monosiphouic stems, an oblique joint some little way from their bases, and, below that, 

 transverse joints which make long and short internodes to the base. 



Cauline nematophores form a line up the central fascicle of the main stem and 

 branches. 



Hydrocladia are of a pale straw colour, not closely set ; they branch alternately 

 from the upper side of the branchlets, one from each internode, and there is one 

 nematophore on each internode above this which is long and tubular and bends in the 

 opposite direction to the hydrocladia. 



Near the base of each hydrocladia there is a solitary nematophore ; then follow 

 hydrothecae, closely set, separated by transverse joints. They are beautifully trans- 

 parent and elegant, with an even, outwardly curved rim, and are about twice as deep 

 as they are wide, having no anterior fold (fig. 1a). 



The mesial nematophore i^eaches about halfway up the hydrotheca, is adnate below, 

 tubular and diverging outwards above, with two orifices. The lateral nematophores 

 are tubular, adnate to the hydrotheca below its rim and rising about as much above 

 it. The intrathecal ridge is very near the base of the hydrotheca and reaches more 

 than halfway across it. 



Between each branchlet on the upper portion of the stem is a string of nemato- 

 phores in threes, sometimes as many as twelve sets in a line (fig. 1b). 



Gonosome not present. 



Locality: Off Mount Lavinia and Kaltura ; also Station I., off Negombo. 



Lytocarpus fasciculatus, n. sp. Plate III., figs. 3 to 3b. 



Trophosome. Colony, stems fascicled, thick, of a pale brown colour ; giving off, 

 at intervals of about an inch, alternate branches, less thick, but fascicled like the 

 stem, and of the same colour (fig. 3). These are about 2f inches in length, and 

 carry closely set hydrocladia, about ^o f an mcn l n g> 0I " a paler colour than the 

 stems, branching alternately and pointing forwards and outwards, with a short 

 cauline nematophore between each. 



Hydrothecge (fig. 3a) closely set, deep, with a crenate margin and a central tooth, 

 the sides sloping upwards from the tooth, and backwards, and being free from the 

 stem for a short distance from the top. Mesial nematophore short, barely half as 

 long as the hydrotheca, free and spout-like for a third of its length. Lateral nemato- 

 phores short and broad, not reaching to the top of the hydrotheca. 



Intrathecal ridge very low down, reaching about half-way across the hydrotheca. 



R 2 



