78 T. KOMAl : STUDIES ON TWO ABERRANT CTENOPHORES 



outside the latter. I could also prepare longitudinal sections of this 

 individual (Fl. 9, fig. 9). This is a typical pianola both in the external 

 and in the internal features; the body is covered with flagella all over 

 the external surface and is filled within by large endodermal cells. 



Anatomical and Histological Features. 



It will be convenient, in giving description of the anatomical and 

 histological features of the animal, to give facts about large individuals 

 as examples; but most of the accounts given may be considered to 

 apply to smaller individuals as well, unless otherwise be stated specially. 



Epidermis . 



The epidermis of the dorsal side of the body is very simple as 

 compared with the same of ordinary ctenophores. It consists entirely 

 of ordinary epithelial cells and comprises no glandular elements altogether. 

 It shows some topographical differences in thickness, being thickest in 

 parts forming ribs (25-30 /i) and thinnest in regions between them (4-6 /.«). 

 The dorsal epidermis is constructed mostly with a few, one or two, 

 cell layers throughout, irrespective of the thickness, so that the individual 

 cells are tall and cylindrical where the epidermis is relatively thick, and 

 low and flattened where this is relatively thin. 



The cells forming comb-plates (PI. 9, fig. 2) are cone-shaped with 

 the apex turning outside and carrying the cilia of the comb. Each 

 comb-plate consists of an assemblage of such cells, with seven or eight 

 cells in each vertical row, and three or four in each transverse row. 

 The two consecutive plates in the same rib are separated from each other 

 by seven or eight ordinary epidermal cells. The epidermis of the ventral 

 side shows distinct ciliation all over. It Ts somewhat thicker than the 

 dorsal epidermis almost everywhere, measuring usually 20-25 /i. 



Abor al Sense- o rg a 11 . 



The aboral sense-organ (PI. 9, fig. i) is constructed similarly as 

 in ordinary ctenophores. It is globular in shape. Its wall consists of 

 slender ciliated cells, and shows nuclei in the whole thickness in three 

 or four strata, except at the bottom part where the nuclei are not found 

 in the superficial half of the thickness. An otolithic mass {at) is situated 



