MONOGEAPH OF JAPANESE OrHIUEOIDEA. 279 



Oral shields pentagonal, or rather lyre-shaped, with straight 

 inner and notched lateral sides and a slightly convex outer side, 

 wider than long, widest at the inner lateral angles ; outer angles 

 perfectly rounded. Adorai shields very long, narrow, meeting with 

 each other within, constricted at about the middle by the second 

 oral tentacle pores and the inner lateral angles of the oral shields ; 

 the outer lobe separates the oral shields from the first ventral and 

 lateral arm plates ; the inner lobe is wider within than without. 

 Oral plates parallel to the adorai shields, also long and narrow. 

 Four or five oral papillœ on either side, close-set, inner ones 

 longer, narrower and acuter ; the outermost one is very wide and 

 short. Besides, there occur two or three long, conical, acute 

 apical papillœ in each jaw. Teeth conical, acute, stout. 



Arms slender, uniformly tapered outwards. The first dorsal 



arm plate is exceedingly small, situated between the pairs of 



radial shields and of arm combs ; the second is also rather small. 



Tlie third is the largest, pentagonal, with very short inner side 



and rounded outer angles, about as long as wide. The fourth is 



similarly pentagonal, but longer than wide, and the inner side 



much shorter. These plates are in contact with one another, but 



the rest are separated by the lateral arm plates, rhomboidal, with 



acute inner and rounded outer angles, longer than wide. They 



constantly diminish in size outwards, and become exceedingly 



small near the extremity of the arms. Lateral arm plates flared, 



meeting both above and below, except in the first joint, in which 



they do not meet below, and the first three or four free joints, in 



which they do not meet above. First ventral arm plate not very 



small, hexagonal, with very short lateral sides and rounded angles, 



much wider than long, about as wide as, but shorter than, the 



next plate. The latter is the largest, hexagonal, with very short 



