254 PROF. F. J. BELL ON THE GENUS AMPHICYCLUS. [May 6, 



There are uo calcareous plates or spicules developed in the walls 

 of the body or of the tube-feet, the only calcareous deposits being 

 the terminal plates of the tube-feet, and the delicate and elegant 

 bars which are found in the tentacles '. 



The integument is very thin anteriorly, but increases considerably 

 in thickness in the hinder part of the body, where it is quite stout. 

 When its walls were cut through, the anterior portion of the body- 

 cavity was found to be filled with a large number of stout, rather 

 short genital tubes, which branched only once or twice, but were so 

 numerous as to obscure considerably the underlying parts. The 

 retractors of the pharynx are inserted behind the middle point of 

 the body ; two of them are remarkable for approaching and uniting 

 with one another ; under the band thus formed, on one side the 

 intestine passes twice. The intestine is very delicate. No Polian 

 vesicle was detected, and it is probably of comparatively small size ; 

 the so-called water-lungs extend forwards to the anterior end of the 

 body. 



The characters presented by this form are sufficiently remarkable 

 to justify the establishment of a new genus for its reception. It 

 stands nearest to the two genera instituted by Ludwig — Echino- 

 cucumis and Actinocucumis ; but it differs from them both in the 

 important character of the regularly paired disposition of the radially 

 placed smaller tentacles. With them, it differs from all other 

 polychirote (or Deudrochirotse with more than ten tentacles), and 

 agrees with the more simple of the decachirote Dendrochirotae in 

 having the sucker- feet confined to the ambulacra. 



In consequence of the definite disposition of the tentacles in two 

 cycles, I propose to speak of it as Amphicyclus, this form of the 

 name being sufficiently different from Amphicyclia 2 . 



The Generic Characters appear to be : — Stichopod arrangement 

 of the suckers associated with the possession 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. 



As there is only one species known, the discrimination of the 

 specific characters is, of course, unsafe ; but these appear to be : — 

 (1) Complete absence of rods or spicules from the walls of the body 

 or tube-feet ; (2) attenuation of the hinder end ; (3) thinness of 

 integument of anterior end ; (4) large number of genital tubes. 



As the locality is known (lat. 41° 12' N., long. 140° 45' E.; 

 43 frns., sand and mud), I propose the specific name oijaponicus. 



The useful classification proposed by Professor Semper in his 

 magnificent work has been universally adopted by systematists since 

 the year 1868 ; in it the Dendrochirotous Pneumonophora were 



1 In Ciicumaria frondosa, where calcareous deposits are reduced to a mini- 

 mum, there are well-developed plates in the tentacles ; and Thy one okeni (see 

 Brit. Mus. Cat. ' Alert' coll.) has rods in the tentacles only. 



2 Haeckel, Jenaische Zeitschr. vol. xv. 



