586 



TAKU KOMAI : 



colourless clisc-like body is more or less convex on the dorsal side and 

 measures 0.5 — 3.00 mm. in diamètre. The smaller and evidently the 



Fig. 1. 



younger of the specimens collected 

 agree very well in general appearance 

 and structure with the descriptions 

 and figures given by KOROTNEFF and 

 HEIDER, so that a detailed description 

 of those specimens may be dispensed 

 with. Only let the following be men- 

 tioned : The gastrovascular system is 

 represented by a connected pair of 

 cavities, each of which is laterally 

 divided into four peripheral pouches ; 



Gastrodes parasiticitm Korotneff, at an the Oesophagus (œ) is not laterally 

 early stage of development. Dorsal view. One compresscd . the tentacle apparatus (/. 



of t'ie youngest individuals observed by the 



author, xao. œ Oesophagus, m.c Meridional b) is indicated by mere thickenings of 

 canal, t.b Tentacle basis. the epidermis, and the aboral sense- 



organ by a shallow depression containing as yet no otolithic mass. It 

 is evident that both KOROTNEFE and HEIDER had before them only 

 such young individuals as above. Individuals of the above simple 

 organization pass by gradations into those which are larger and show 

 unmistakable ctenophoran characters. 



Fig. 2 shows one of the largest individuals that came under obser- 

 vation, as seen from the side. Such an individual is provided with 

 eight rows of comb-plates (c), besides showing distinct indications of an 

 aboral sense-organ (s) and the tentacle-apparatus (/., /. b). 



The aboral sense-organ, situated at the apex of the more or less 

 convex dorsal surface, includes a distinct otolithic mass in the centre of 

 the cavity. In all its structural details, the organ closely agrees with 

 that of ordinary ctenophores. Each comb-plate row consists of about 

 twenty plates made up of fairly long cilia. The tentacle-stem (/) is 

 represented by an unbranched stump-like rudiment ; the tentacle-basis 



