388 AIIT. 2. — H. MATSUMOTO : 



tion of the A7nphiiir(i,-{i,toni>, and the Ophiotrichidar, those of Amphiura vadicola (PI. Ill, fig. 

 13), A. trachydisrji, (PI. IV, fig. 4) nnd Ophiocentrus verticUldtas (PI. IV, fig. 5) are double and 

 very small, a character of the Amphiura-gronp. The common outline of the oral and dental 

 Ijlates of all the representatives here illustrated is X-shaped, thoiigh that of Amphiacnntha 

 dlviduii is slightly atypical owing probably to the fact that the specimen is very small and 

 young. This diaracler is common to the Amph'mridcv and Ophiotrichidc; in contrast to those 

 groups of the ChUophiurida with well developed masticatory apparatxis. The teeth are very 

 sloiit, squarish, with wide and tnuicated tips, and the oral frames are very stout and have 

 well developed lateral wings, charactexs common to the Amph'mrlda;, Ophiotrichidfr, Ophioceramis, 

 Ophumereidinœ and Ophiocomida;. The genital ])lates in Ophiopholis acideato. (fig. 10) and Ophio- 

 centrus verticilldtiis (fig. 5) bear each a very conspicniovis, ball-like articular condyle on the 

 <lorsal side near the outer end ; this is a charactrristic of the Orxdhophhtridd., as already 

 «explained. They are firmly attached to the basal vertebra;, a common characteristic of the 

 Amphiuridii; and Ophlotrlchida; in contrast to all the other ophiurans. The genital scales of 

 Ophiopholis (iculeatd (I'l. Ill, fig. 10) are wide, thin and leaf-like and articulate with the genital 

 plates near the outer ends of the latter ; this is al.so a character of the Grudhophlurida and 

 Ijart of the Chilophinridd. The vertebrii; are seen in fig. 10, PI. Ill (Ophioph lis aculecda) and 

 fig. 5, PI. TV (Ophiocentrus verticlllidua); their dorsal surface is rhomboidal and not very 

 deeply notched at the inner end, a common character of tlit; Amphilepidihr and Amphiuridœ, 

 as well as several groups of the other orders, in contrast to the Ophioirichida'. 



n. IV, figs. 6-8 illustrate the internal structures of the Opfdotrichidn;. In all the species 

 here illustrated, viz. Ophiothrix nereidiiKi, (fig. (>), 0. koi-enna, (fig. 7) and Ophiothela dana; (fig. 

 8), the peristomial i)lates are simple and small, a common character of part of the 

 Amphhiridii; and the OpMof.rirhidn; ; the common outline of the oral and dental plates is 

 X-sbapod, a common character of the Amjihliirida; and Ophiotrlchidd' • the teeth are very stout, 

 s<]Uarish, with wide and truncated ends, and the oral frames are very stout and have well 

 developed lati-ral wings, characters common to the Amph'mrldd', Ophintrlcfddti;, Ophioceramis, 

 Ophionereidimr and OjMocoiiudd; ; the genital jilates bear a very conspicuous, ball-like articular 

 condyle on the dorsal side near the outer end, a characteristic of the Gnathophiurldu ; the dorsal 

 surface of the vertebra (except the very basal ones) is Y-shaped, a characteristic of the Ophio- 

 trichidc: in contrast to the .\mphUe2Hdidœ and Amphiuridd; • the genital scales are wide, thin and 

 leaf-like, a character of the (hvdhopk'mridd and part of the Chilophiaridd. The radial shields 

 are, as seen in fig. 6 {Ophlidhrlx wrcidhk'i), very largo and triangular, a common character of 

 most of the genera of the OpJiiotrichidd!, and have a very largo articular socket to fit to 

 the ball-like articular condyle of the genital plate, a characteristic of the (Jii'Uhophiurida. 



PI. V, figs. 1-5 show the internal structures of A.sirophiiira Jmwumurni. The peristomial 

 jilates are absent, though the peritoneal membranes of the oral region and other parts contain 

 very fine scales (fig. 1). It is stated by L\'M.\n, that Ophiopliidhus medusiv, lacks the peristomial 

 ] liâtes. The oral frames are very long and slender, also reminding us. of those of Opkioplivihus 

 iiifdusd;. The oral plates are al.so slender, ami the dental plate is stout. The genital 



