CLASSIFICATION OF THE SPECIES 259 



Sub-genus Acoelothecia, sub-gen. nov. 



Colony small or large and branching, formed of a meshwork of bars and spines without 

 any definite coenoecial cavities. Spaces between the meshwork irregular and continuous 

 and occupied in common by the zooids and their buds. 



C. kempi, n.sp. Colony small and tuft-like or large and branching. Inhabited part 

 of coenoecium formed of an elaborate meshwork of bars and spines. Spines found all 

 along the sides of branches; not related to ostia. Colour of coenoecium light brown to 

 reddish brown. Length of zooid i-8 to 2 mm. Arms five pairs, with end-swellings with 

 refractive beads. Off Falkland Islands; off South Georgia. 



NEW DATA SUMMARIZED 



1. Two kinds of zooids are found in C. hodgsoni. Red zooids with twelve arms 

 (female) and brown zooids with ten or eleven arms (males). Dimorphism being thus 

 established, it is possible that C. inaeqnatus of Andersson is synonymous with C. hodgsoni, 

 as suggested by Ridewood. 



2. In C. densus a gill sac lies between the external gill opening and the pharynx. 



3. C. fumosus is a new species, the zooids of which resemble those of C. nigrescens, 

 but the coenoecium is formed by the agglutination of minute sand particles. 



4. C. kempi is a new species which constructs a coenoecium formed of a meshwork 

 of bars and spines. Because of this unique structure and the absence of distinct tubes 

 for the zooids it is found necessary to create a new sub-genus Acoelothecia. 



5. The red line on the proboscis and the pigmentation in the oviduct are believed 

 to be sensory in function. 



6. It has been shown that the dorsal vessel gives off two branches — the pharyngeal 

 vessels- — which enter the gills. 



7. The main ganglion gives off the pre-oral plexus; and the paired post-oral nerves 

 divide into three branches. 



LIST OF LITERATURE 



Andersson, K. A., 1903. Eine Wiederentdeckung ion Cephalodiscus. Zool. Anz. xxvi, no. 697, pp. 368-9. 



1907- I^ie Pterobranchier der Schwedisclien Siidpolar-Expedition, igoi-1903. Wiss. Ergebn. Schvved. 



Siidpolar-Exp. v, Stockholm, pp. 1-122. 

 Cole, F. J., 1900. On the Discovery and Development of Rhabdite-' cells' in Cephalodiscus dodecalophus. 



J. Linn. Soc. Zool. xxvn, p. 256. 

 Gilchrist, J. D. P., 1915. Observations on the Cape Cephalodiscus (C. gilchristi, Ridewood) and some of its 



early stages, with an appendix by S. F. Harmer. Ann. Mag. Nat. Hist. ser. 8, xvi, pp. 233-46. 



1917- On the Development of the Cape Cephalodiscus (C. gilchristi, Rideioood). Quart. J. Micr. Sci. 



LXII, pt 2, pp. 189-211. 

 Gravier, C, 1912 a. Sur les Pterobranches rapportes par la seconde Expedition antarctique frangaise . Comptes 

 Rendus Acad. Sci. cliv, Seance du 28 Mai 1912, pp. 1438-40. 



