﻿AMPIIIURA. 



115 



Ophiactis sexradia Lutken. 



Opldolepis sexradia GnUBK. Wiegraann's Arcliiv., p. 342. I. 1857. 

 Ophiactis sexradia Lutken. Addit. ad Hist. Oph., II. p. 126. 



LIST OF SPECIMENS. 



227 

 403 sp. 



Museum of Comparative Zoology. 



I A. Garrett. 



12-)-| Sandwich Islands, 

 . . I Zanzibar. 



AMPHIUEA Forbes. 



Type of the Gends, A. fiUformis. 



Disk small and delicate, covered with naked, overlapping scales, and 

 furnished with uncovered radial shields. Teeth. No tooth-papillae. 

 Six (rarely eight) mouth-papilla; to each angle of the mouth. Arms 

 slender, even, more or less flattened. Arm-spines short and regular, 

 arranged along the sides of the side arm-jjlates. Two genital slits to 

 each interbrachial space. 



GROUPING OF SPECIES HEREIN DESCRIBED. 



Arms long and slim ; middle arm-spine with a cross-piece at the end, A. JiUformis. 



Arms very slim and of great length (often twenty-four times as long as ^ 



diameter of disk), tapering only at their tips ; outer mouth-papilla V A. gracilUma. 



broadest ; radial shields very long and narrow, J 



One mouth-papilla placed above the rest ; radial shields long and narrow, -; 



Outer mouth-papilla broadest; under arm-plates pentagonal; arms of] 

 moderate length (about eight times the diameter of the disk), j 



Outer moutli-pajiilla much the broadest ; under arm-plates pentagonal ; ) 

 side mouth-shields large and meeting within, i 



Hollolli. 

 Chiajii. 

 geminata. 



squamata. 



tenera. 



pugetana. 



atra. 



urtica. 



Under arm-plates broader within than without, A. 



Some of the disk-scales with toothed edges, ' A. 



Mouth-papillae equal, separated ; under arm-plates square ; upper arm- 

 plates large, overlapping, wider without than within, with rounded Y A. occidentalis. 

 outer corners. 



