16 Proceedings of the Biological Society of Washington. 



the central portion of the arm there are six arm spines, the lowest very 

 slightly longer and stouter than the next, which again is very slightly 

 longer and stouter than the others, these being subequal ; and in the 

 outer portion of the arm there are five arm spines, and distally four. 



The under arm plates are about one-third broader than long, rectangu- 

 lar, with blunted corners and concave lateral and distal borders. In the 

 enlarged proximal portion of the arm a rounded ridge appears on either 

 side of each under arm plate, just within the lateral border; nearer the 

 base of the arm the ridges move toward each other, becoming at the 

 same time more and more strongly curved so that at the base of the arm 

 the tentacle scale on the under arm plate occupies the center of a deep 

 half cup shaped depression. 



The tentacle scales are two in number, rather large, broad, and well 

 rounded. 



Type.— Cat. No. 15,470, U. S. N. M. , from Hong Kong. 



