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152 



THE OPHIURIDtE. 



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scales; their adradial side is almost straight, the abradial curved ; inner end 

 shortly pointed, outer end so truncated that there results a rather deep 

 curve above the arm. Outside the radial shields there is a sinsrle row of 

 small scales or a single narrow scale. Usually the inner end of the genital 

 scale is distinct. The margin of the disk is re-enteringly curved, the edge 

 rounded. 



Three tapering arm-spines, the middle the longest, a little longer than 

 an arm-joint. Two tentacle scales, wide, rounded, forming a right angle 

 with each other. 



Color in alcohol : disk bluish, often with a reddish tint at the outer end 

 of the radial shields; arms white or pale brown. 



Several large specimens from Stations 3393, 1020 f. ; 3394, 511 f . ; 3398, 

 1573 f.; and 3429, 919 f. 



A large, fine species, which is not very variable. The mouth shields, as 

 above said, are the most variable in form; outer edge of the ventral plates 

 sometimes straight or a httle convex. The dorsal plates may be separated 

 also on the inner joints. There arc seldom three outer mouth papilla?, and 

 never on all the mouth angles of the same specimen. One specimen (3398) 

 has a small papilla between the two outer mouth papilla) (Fig. 4) ; also the 

 mouth and side mouth shields are here of another form than the common 

 one. However, there can be no doubt that it is the same species. 



From Station 3392, 1270 f, there are three specimens, from Station 

 3429 one, which diifer somewhat from the other specimens of A. Diomedew 

 (Figs, 5-7). They are all smaller than the specimens from the other sta- 

 tions, and it may be they arc only younger specimens of ^. Diomcdece ; or it 

 may be they ai-e to be considered as a variety of that species; they can 

 scarcely be regarded as a separate species. Differences from the typical form 

 are seen in the shape of the mouth and the side mouth shields; but on 

 that feature no stress can be laid, as it is also rather variable in the typi- 

 cal form ; nor is it wholly alike in these four specimens. The first ventral 

 plate has a distinct angle within, and is rather large. In the specimen from 

 Station 3429 the dorsal plates are transversely oval, not of the typical form. 

 The margin of the disk is convex. 



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