S6 '!'. KOMAI: STUDIES ON TWO Al'.lCRRANT CTENOPHORKS 



•granules are found in the parts forming the margin of the area just 

 referred to, showing that here exist the matrix cells of the granules. 

 The cilia supporting the otolithic mass are still v^ery fine. On either 

 sagittal side of the sense-organ, is found a rather tall crest-like process, 

 which is ciliated all over its inner side — this part represents the polar 

 plate without doubt. Probably, the process is divided into a few lobe- 

 like portions in some later stage as we have seen in the adult animal. 

 The tentacular apparatuses are disposed nearly vertically, instead of 

 horizontally as they are in the adult, although they diverge somewhat 

 from each other at their oral ends. They present a structure nearly the 

 same as in the youngest cydippid larva described above. The tentacle- 

 stem is inserted at the end of one-third of the length of the tentacle-root 

 from the aboral end (Pi' 7, fig. 13; /. st). It is very much longer than 

 it was in the earliest stage of the larva mentioned above. The core of 

 the stem shows already the muscular feature clearly; its growing point 

 exists near the oral end of the tentacle-root. A few accessory filaments 

 are attached to the tentacle-root at the parts directly below the point 

 of insertion of the tentacle-stem and above the middle point of the 

 length of the tentacle-root. The filaments are covered by the rudiments 

 of colloblasts all over. The mouth shows itself as a slit-like aperture 

 elongate in the transverse direction. The stomodaeum is divided into 

 three parts, viz. the external and the internal halves of the pharynx 

 and the oesophagus. Of these, the external half of the pharynx is most 

 spacious, it is flattened, like the mouth aperture, in the transverse plane, 

 the diameter of the cavity measured along the transverse axis being 

 about four or five times the length of the diameter in the sagittal 

 direction. The internal half of the pharynx shows a lateral compression 

 too, but in the direction perpendicular to the former, its diameter in the 

 .sagittal direction being about twice the length of the diameter in the 

 transverse direction. Lasth', the oesophagus is flattened in the same 

 jilane as the internal half of the pharynx; its oral part is produced into 

 the lumen of the latter for a short distance, so as to be telescoped into 

 that. 



The configuration of the stomodaeum may be understood more 

 clearly by a collaboration of cross-sections. In PI. 7, fig. 19 is shown 

 a section from a level very near the oral end of the body. It exhibits 

 the cro.ss-section of the external half of the pharynx which is compressed 

 in the way described above. Next fig. i<S has been taken from a 

 section passing through the boundary of the external and internal halves 



