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142 



THE OPHIURIDiE. 



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p. 110): ^'As a rule the number [of arms] is six, and of these two or three 

 are almost always smaller than the rest. The arms vary much in number 3 

 occasionally a specimen may be seen with only one, A young one had five 

 arms about 3.5 mm. long, the diameter of disk bein'g 1.2 mm." Beyond 

 that he gives no further evidence as to the point in question, only in the 

 Challenger Report he definitely says it to be so (p. 113). On page 116 he 

 says, *^ The so called adult of 0. Mullen has five arms." It thus seems' that 

 Lymak was, however, not wholly convinced that it was so. 



Also to 0. 2dctna Lym. this species will be closely related; but as no 

 figures are given of tliat species, it is almost impossible to say anything 

 definitely about it. From the notice in the Challenger Report, page 116, it 

 seems that 0, plana has six arms ; in the original description nothing is said 

 of this. 



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25, Ophiactis dupKcata (Lym.). 



riate VI. Figs. 1-3. 



Amphiura duplicata Lyman. 111. Catal. Mus. Comp. Zool., No. VIII., Part II. p. 19. Plate V. Eig. 78 ; 



outline, Eig. 87- 

 Challenger Ophiuroidea, p. 136. Plate XYII. Tigs. 10-12. (7G), p. 251. 



KoEiiLER. (61), p. 74.; (127), p. 49. 





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fC 



Ci 



To this species we refer with a httle doubt some specimens from Stations 

 3380, 899 f. (together with ft profundi), and 3407, 885 f. As this species 

 has hitherto been known only from the Atlantic, it is important to be quite 

 sure of the identification; but the figures hitherto given thereof are not 

 quite satisflictory, so we are not wholly convinced of the identity. We 

 therefore give figures of our specimens. 



The differences found between the Atlantic and the Pacific specimens 

 are rather unimportant. The mouth papilla), mouth and side mouth shields, 

 and the ventral plates, show some small differences, as will be seen by com- 

 paring Lyman's figures with ours. But, as there is some variation in our 

 specimens in respect to mouth papilljB (3-5), mouth shield (sometimes re- 

 stricted at the outer end, not rounded), and first ventral plate (more rounded), 

 there cannot be much stress laid upon that. It is to be remarked that the 

 outer edge of the ventral plates is a little re-enteringly curved from outside 

 the disk ; whether that is a real difference or not cannot be seen from 

 Lyman's figures and description. Outside the radial shields there is a little 

 very narrow scale. Finally, the (five) arms appear to be a little shorter 



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