70 



IIIKOSIII OHSHIMA : 



disappeared Ph. japonicus. 



dd. In the introvert rosettes only ; in general perisomc tables with 

 spire consisting of four or more pillars. 



c. Tables very thinly scattered on body surface, so that the 



skin is soft to the touch ; spire of tables rudimentary 



Ph. fragilis. 



ce. Tables profusely present on body surface, rendering the skin 

 rough to the touch; spire of tabic very tall..../'//, hypsipyrgus. 



Genus Amphicyclns Bell. 



Amphicyclus Bell, 1884 [5], p, 254. 

 Type. — A. japonicus BELL. 



The generic diagnosis given by BELL is as follows : — ■ 

 " Stichopod arrangement of the suckers associated with the pos- 

 session of more than ten oral tentacles ; the tentacles in two circles ; 

 those of the inner are arranged in pairs, are ten in number, radial in 

 position, smaller than those of the outer circle, in which there are 

 fourteen subequal tentacles. There are no calcareous pharyngeal 

 plates, and two of the retractors of the pharynx are united with one 

 another." 



Now, if my identification of the specimens on hand with A. 

 japonicus be right, I should propose to define the genus as 

 following : — 



Tentacles of unequal size 25 — 30 in number, present in three 

 orders. Small tentacles in five pairs, which are radial in position and 

 regularly alternate with pair of larger ones, form the inner circle. 

 Pedicels limited to ambulacra, interambulacra being naked. Radial 

 segments of calcareous ring without posterior prolongations. Calcareous 

 deposits of general perisome in the form of tables with spire con- 

 sisting of two pillars. 



Except in tentacle number, this genus closely approaches Pscu- 

 docucumis. Two species belong to the genus, namely A. japonicus 



