238 ART. 2. — H. MATSUMOTO : 



/^/w«?^/ (Ljüngman) and Opliiuroleph carinata {HTiwi:n){=: Ophiogli/pha 

 deshayesl Lyman) appear to be almost similar to Ophiura kinbergl 

 in their internal structm-es. Those forms with double peristomial 

 plates have always short oral frames and short, discoidal basal 

 vertebra?. 



The Ophiolepidince are fairly uniform in their internal' struc- 

 tures, the two opposite extremes being represented by Ophio- 

 mu><'mm and OpJdoceranm. In Ophiomusium trychnum Clark, which 

 is a representative of the species with only two pairs of tentacles 

 to each arm base, the peristomial plates are double and exceeding- 

 ly small, the oral plates are very long and slender, and the oral 

 frames and basal vertebra? are also extremely long. In Ophiomusium 

 cancellatum Lyman, which is a representative of the species with 

 three pairs of tentacles to each arm base, the internal structures 

 are almost similar to those of the foregoing, but the peristomial 

 plates are larger and the oral plates, oral frames and basal 

 vertebra? shorter. In Ophiozonella longispina (Clark), the peristomial 

 plates are comparatively large, the oral plates short and stout, the 

 oral frames more or less short, and the basal vertebra? short and more 

 or less discoidal. In these three species the first vertebra, and 

 not the second, is the shortest. In Ophiomusium, the teeth are 

 very slender, while in Ophiozonella, they are more or less squarish 

 and stout. In Ophiozona impressa . (Lütken), Ophiolepis cincta 

 Müller & Troschel and Ophioplocus japomcus Clark, the peristo- 

 mial plates are comparatively large, the oral plates and frames 

 very short and stout, the basal vertebra? very short and discoidal, 

 the second being the shortest, and the teeth more or less squarish 

 and stout. In Ophioceramis januarii (Lütken), the peristomial 

 plates are also double, but very small and transversely bar-like, 

 the oral plates are very short and stout, the oral frames very 



