58 T. KOMAI : STUDIES ON TWO ABERRANT CTENOPHORES 



of very tall and vacuolated cells, as also the wall on the opposite side 

 adjacent to the pharynx; on the other sides, the canal is lined with a 

 much lower, epithelium. It is no doubt that, the canals just referred 

 to have developed from the endodermal pouches of previous stages. It 

 is also certain that, they develop into the subtentacular pouches to be 

 described in the next stage. Attention may be also called to the 

 presence of a pair of outbulgings at the middle parts of the sagittal 

 wall of the infundibulum (PI. J , fig. i6; s. s. p). They are very short 

 and only indicated, yet, it is very probable that, they are the rudiments 

 of the subsagittal pouches to be seen in the next stage. The epithelium 

 shows there sparse but distinct ciliation. The parenchyme of the body 

 consists of gelatinous tissue for the greater part, with some isolated cells 

 scattered about, and also with small fibrous bodies apparently to be 

 identified as the rudiments of muscles; the latter are found rather 

 abundantly around the mouth. The parts about the tentacle-sheath 

 contain some pigment-cells. 



Metamorphosis . 



Now returning to the larva liberated from the &^^ (PI. 2, figs. 13, 

 14); it swims about very actively by means of combs, and while so 

 doing, it moves the parts about the tentacle-apparatus vigorously inwards 

 and outwards, which movement gives the tentacles hanging from the 

 aperture of the tentacle-sheath at the top of that part a violent swinging 

 motion. The swimming movement of the larva is highly characteristic. 

 Instead of the gentle and steady locomotion by means of the regular and 

 harmonious beatings of comb-plates of ordinary ctenophores, the larva has 

 a quite sudden and jerky method of locomotion reminding one somewhat 

 of that of copepods. This is evidently due to the disproportionate length 

 of the cilia of the combs for the small size of the larva, the cilia 

 performing sweeping movements and bringing about the peculiar jerky 

 locomotion of the larva. The length of the time during which the larva 

 performs such movement varies somewhat. I found in some cases the 

 larva remain in that state more than one day, while, a larva that came 

 under my examination one day in the early part of September of 191 8, 

 passed the stage in only four or five hours. Sooner or later, the larva 

 takes to swimming much less frequently than before but remains most of 

 the time at the bottom. Then, it begins to adhere there by means of 

 the extended surface of the external half of the pharyn.x and somewhat 



