* 



ON CTENOPHORES OF THE NEIGHBOURHOOD OF MISAKI. 461 



A very young specimen closely approaching both in size and in 

 structure the one figured by MAVF.R (1912, PI, X, fig. 55) was captured 

 at Misaki, Dec. 29, 1916. It measures about 10 mm. from end to end 

 of horizontally extended lappets. The auricles are short and semilunar 

 in shape. In each octant of the body only a single comb is fully developed; 

 the second exists but in a rudimentary state, although it may bear a few 

 cilia in some octants. The condition of lappet-canals is nearly precisely 

 the same as depicted in the figure above referred to. The tentacles 

 are distinct and are furnished with a few number of branches. The 

 tentacular canals are also very distinct. These proceed from the infundi- 

 bulum and terminate each in two branches at the base of tentacle. 

 The animal was perfectly colourless in the fresh state. In sections of 

 this specimen I have ascertained the presence of colloblasts in the 

 tentacles. 



Genus Cestum, Lesueur. 

 {Cestus, Chun.) 

 5. Cestum amphitrites Mertens. 



Cestum ärtiphitrites, Bigelow, 1912, p. 396. 

 Cestus amphitrites, Moser, 1908, p. 14. 

 Cestus veneris, Chun, 1880, p. 301 (partim). 

 Cesium reiteri*, Mayer, 1912, p. 44 (partiin). 



Cestus pectmalis, Bigelow, 1904, p. 267, PI. viii, tig. 30. Moser, 1908, p. 13. 



There seems to exist no important structural difference between 

 this species and C. veneris, as far as can be judged from the existing 

 descriptions of the latter species. The body is long and ribbon-shaped, 

 slightly narrowing towards both extremities which are broadly rounded 

 The aboral margin is vaulted, and is 2.5 times as wide as the oral 

 margin which is pronouncedly concave. The body is thickest midway 

 between the oral and aboral margins along the line of subtentacular 

 canals. The apical sense-organ is slightly depressed beneath the level 



