190 7. J FROM THE CAPE VEPDE ISLANDS. 507 



shai'p spine lying almost parallel to the continuation of the 

 branch. The spiny apjjearance of the branch- bearing processes 

 of the stem when denuded of their branches is also noteworthy 

 (c/. AUman, 1888, p. 72). 



Locality. Porto Praya, Cape Verde Islands : piles of pier ; 

 12th August, 1904. 



Other localities : — Off Bermuda, 30 fathoms (' Challenger ') ; 

 Cape Verde Islands, 25 metres {Versluys); on floating gulf -weed 

 {^Albatross ') ; N,W. of Cape Blanc (Soudan), in 55 to 60 metres 

 {Billard, 1906). 



In the colonies examined, the gonophores were all male and in 

 an advanced stage of development. Their structures resemble 

 those of Sertulai-ia inmnila as described by Nutting (1904, pp. 26 

 et seq.), but in most, owing perhaps to the advanced stage of the 

 gonophore, the blastostyle is comparatively small, and in no case 

 could be observed to terminate in a thickened plug or " Decken- 

 platte." On the other hand, delicate strands of ectoderm stretched 

 from the outer coat of the gonophore to the gonangial wall, to 

 which they were attached, thus mooring the gonophore within 

 the gonangium. Nutting, who also has found similai' " gubei-- 

 nacula " in a male gonangium but arising from a sperm-bearing 

 blastostyle instead of from a true gonophore, suggests that they 

 may connect the ectoderm of the blastostyle, or in this case of the 

 gonophore, with a delicate ectodermal layer which in some cases 

 lines the inside of the gonangial walls (Nutting, 1904, p. 29). 

 In these specimens I have been unable to detect the presence of 

 an ectodermic gonangial layer such as Nutting describes. He 

 also suggests that they may possess the nutritive function 

 attributed by Weismann (1883) to the gubernacula of '■'• Sertularia 

 pumila." 



Sertularia l^vimarginata, sp. n. (Plate XXVI. figs. 5 & 6.) 



Several minute colonies, less than 3 mm. in height, spring from 

 a creeping hydrorhizal tube which ramifies over a polyzoon- 

 encrusted frond. The stems are unfascicled and unbranched and 

 are divided into distinct internodes, about 0*3 mm. long, which 

 become much constricted in the neighbourhood of the nodes. 

 The portion of the stem proximal to the first distinct node, which 

 slopes at a high angle from back to front, is athecate, but each 

 internode bears two opposite hydrothecae towards its distal end. 



The hydrothecfe rest upon a bulging portion of the internode 

 and are somewhat ventricose, the bulging poi-tions meeting on the 

 front of the stem, but being slightly separated, for O'Ol mm., 

 behind. For less than half their height they are adnate to the 

 stem, but the distal portion (about 0-28 mm. in length) bends 

 sharply outwards, so that the apparent upper sides form an 

 almost straight horizontal line. The free portion becomes 

 gradually constricted and tube-like towards the margin, which is 

 smooth and is characterised by a shallow sinus on its upper edge, 

 at the base of which is attached a disc-shaped adcauline operculum. 



