6o T. KOMAT : STUDIES ON TWO AT5ERRANT CTENOPHORES 



shape and that were taken from the alcyonacean host, the smallest and 

 youngest observed was the one only i mm. in the diameter (PI. 7, fig. 

 22). This specimen showed some features standing between the last 

 larval stage and the adult. In the dorsiventral view, the pharynx {ph!) 

 exhibits a quadrate shape somewhat elongate in the sagittal direction, 

 and the oesophagus {oe) is fusiform in the optical section, both parts 

 therefore approaching the definitive state very closely. Moreover, the 

 tentacular apparatuses {t) show no feature to distinguish the specimen 

 from the adult, except for the shortness and simpleness of the stem, and 

 the sense-organ {s) is nearly the same as that of the adult. The most 

 notable point in the internal structure of this specimen is the condition 

 of the gastro-vascular system : the system consists of eight broad and 

 subequal pouches arranged radially around a central cavity representing 

 the infundibulum and a canal system occurring in the peripheral part 

 of the body. Of the eight pouches, four are placed in relation with 

 the tentacle-basis on each side of the transverse plane and may be 

 called the subtransverse pouches {s. t. p), while the remaining four are 

 situated on each side of the sagittal plane and may be called the 

 subsagittal pouches {s. s. p). It is without doubt that, the subtransverse 

 pouches have developed from the four canals described in the larva 

 previous to metamorphosis, while the subsagittal pouches have arisen 

 from the four outbulgings that were then very short and only indicated. 

 It is no less certain that, subsequently, each of the former pouches will 

 give rise to the tentacular and subtentacular canals, while each of the 

 latter will develop into the subpharyngeal canal. The peripheral canal 

 system {br. c) is relatively broad and shows only sparse branchings and 

 anastomoses. The relation of those canals with the central pouches 

 could not be studied clearly, yet, it is certain that, they are commu- 

 nicated with the latter somewhere in their course. 



The central part of the body which contains the pouches are sit- 

 uated on somewhat higher level than the peripheral parts which show 

 branching canals, indicating without doubt that, the former has been 

 transformed from the central elevation of the metamorphosing larva. 



It is interesting to note that, the specimen under description 

 exhibits a singular resemblance in structure with the young stage of 

 Gastfodes parasiticiim Korotneif to be described in the second part of 

 this pai)er. This is especially so in the condition of the gastro-vascular 

 system, which consists of eight ])Ouches subequal in size and arranged 

 radially around the infundibulum, four in relation with the tentacular 



