510 MR. JAMES RITCHIE ON HYDROIDS [May 28, 



leaves, which ai-e altogethei' free from one aiiothei-. Every leaf 

 bears a row of 6 or 7 large bulging nematophores on each margin. 

 The coenosarc from which the portions supplying these nemato- 

 phores branch off runs up one side of the leaf, sending ofi' as it 

 passes a short process into each nematophore on that side, and 

 then having passed a considerable distance up the leaf, sends off a 

 larger shoot which, running backwards, supplies the nematophores 

 along the other side. Conforming witli this branching of the 

 coenosarc, the coenosarc-containing cavity in the leaf also shows a 

 backward-running branch connected with the nematophore- cavities 

 along one side {vide PI. XXIV. tig. 10). Without the walls of 

 this cavity there is a delicate chitinous membrane connecting 

 the nematophores and forming a wing-like extension to the body 

 of the leaf proper. The specific name marginata indicates the 

 presence of this extension. At the base of each leaf along only 

 one side of the corbula there is a very small spur-like nematophore. 

 Locality. Growing on the bottom of lighters : St. Vincent, 

 Cape Verde Islands ; 20th and 80th July, 1904. 



Lytocarpus grandis, var. unilateralis, var. n. (Plate XXV. 

 figs. 1, 2, 3.) 



Many much-branched colonies have been obtained from one 

 locality : the largest, which is fragmentary, is 20 cm. in height, 

 with a stem 6 mm. in diameter above the first branch, and a large 

 basal portion covei'ed with loose hydrorhizal tubes. 



The stem is strongly fascicled and is divided neai- the base into 

 several large branches, which bear smaller branches and so on 

 sometimes to the sixth order. All the branches, except the 

 smallest, spring from their parent branch on the side remote from 

 the stem, a rather inausual arrangement to which the vai-iety 

 owes its name. The hydroclade-bearing tubes are divided into 

 regular internodes, 0-4 to O'S mm. in length, each of which bears 

 an alternate hydroclade almost on its anterior surface. 



The hydroclades, which are borne on a perforated process of the 

 internode, are about 8 mm. long, and are divided into internodes 

 0-35 mm. in length, each with two very strong septal ridges, one 

 opposite the intrathecal ridge and horizontal, the other less distinct 

 opposite the base of the latei'al nematophores and sloping obliquely 

 upwards. 



The hydrotheca? are closely approximated, deep, slightly bulging 

 below, with nine teeth, seven of which are apparent while one on 

 each side is hidden by the lateral nematophore. The anterior 

 tooth is slightly recurved. The intrathecal ridge is distinct and 

 is horizontal, extending around the hydrotheca about i fi-om the 

 base. The mesial nematophores are long, adnate almost to the 

 top of the hydrotheca and then free for some distance. The free 

 nortion varies much in length, sometimes scarcely rising above 

 the hydrotheca on the proximal end of a hydroclade while over- 

 topping those on the distal portion for a considerable distance 

 {cf. PI. XXV. figs. 2 & 3). In the supracalycine nematophores 



