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146 



THE OPHIURIDiE. 



First ventral plate very small, six-sided; those beyond equally wide and 

 long, rather broadly in contact; they have inner angle truncated, outer 



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edge concave^ outer corners rounded, outer laterals almost straight, inner 

 ones re-enteringly curved. Side arm-plates with spine-ridge very little 

 prominent; as usual there is a naked space separating the side plates of each 

 two adjoining joints, that space being distinct also from the dorsal side. 

 Dorsal plates in mutual contact, somewhat more broad than long, with a 

 rounded peak within and without, the latter however very indistinct; inner 

 sides a little re-enteringly curved, side corners rounded. 



Dorsal side of the disk covered with small, overlapping scales, among 

 which the primary plates are not conspicuous. Eadial shields about half as 

 long as the radius of the disk, separated within by more small scales, without 

 by one elongated scale, just meeting at their outer ends. Their adradial edge 

 is straight, the abradial curved ; inner end pointed^ outer end broadly 

 rounded. Outside the radial shields there are more small scales, and there is 

 a rather deep, narrow incisure in the median line. The under side of the 

 disk is quite naked, only the inner end of the genital scales being distinct. 



Five, farther out four, rather short, tapering arm-spines, increasing in 

 length downwards, the lowest being as lo^g as a joint. Two small tentacle 

 scales, not standing at a right angle. 



Color in alcohol : gray. 



Five rather badly preserved specimens from Station 3392, 1270 f. 



This species is very closely related to A. semiermis Lym., and should per- 

 haps not be considered as a separate species. It differs from that species in 

 the form of the mouth shields and the ventral plates; the outer edge is more 

 concave and the outer corners more prominent than in A. seiniermis.^ It is 

 closely related also to A. lanceolata Lym., but In like manner separated from 

 that species by the form of the mouth shield, and the ventral and dorsal 

 plates. 



28. Amphiura polyacantha n. sp. 



Plate IX. Figs. 3-5. 



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Diameter of disk, 8 mm. ; width of arm close to disk, without spines, 

 1.4 mm.; length of arms 10-11 times the diameter of the disk. One 

 rather long, conical mouth papilla on each side, besides the infradental one. 

 Mouth shield a little longer than wide, inner part strongly rounded, outer 



* Wc have had specimens of A. semiermis dctcnnmcd by Ljmaii himself, for comparisou. 



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