12 



ZOOLOGY 



SECT. 



Rhabdopleura (Fig. 714) occurs in colonies of zooids organically 

 connected together, and enclosed in, though not in organic con- 

 tinuity with, a system of" branching membranous tubes connected 

 with a creeping stolon. The collar-region bears a pair of hollow 

 arras each carrying a double row of slender tentacles— the whole 

 supported by a system of firm internal (cartilaginous ?) rods. 

 There are collar-pores and proboscis-pores. The " notochord " and 

 the nervous systems resemble those of Cephalodiscus. A single 

 testis has been found, opening on the exterior by a pore situated 

 near the anus. The female reproductive apparatus is unknown. 



Flo. 713. — Cephalodiscus. Diagi-am of longitudinal section, a. anus; 6ci. ciclomc of pro- 

 boscis ; 6c-. oiulome of collar ; ftci*. ccelonie of trunk ; inf. intestine ; m. mouth ; nrh. supposed 

 notochord ; n. s. nerve-strand ; op. operculum ; res. (esophagus ; or. ovary ; oni. oviduct ; pk. 

 pharnyx ; p. p. proboscis-pore ; ps. proboscis ; st. stomach ; .ttk. stalk. (After Harnier.) 



Cephalodiscus, of which there are twelve species, has been found 

 at various widely separated localities in the Southern Hemisphere 

 (Straits of Magellan, Borneo, Celebes, the Antarctic) : species 

 occur off the coast of Japan and Korea. Some live in shallow 

 water: none have been found at a greater depth than 245 fathouis. 

 Rhabdo])leura has been found at moderate (le})ths in Norway, 

 Shetland, the North Atlantic, France, the Azores, Tristan 

 d'Acunha, Celebes, and South Australia. It seems doubtful if 

 more than one species occurs. 



