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148 



THE OPHIURIDiE. 



29. Amphiura seminuda n. sp 



Plate XI. Figs. 1-3. 



Diameter of disk 6 mm. ; width of arms close to disk, without spines, 

 1 mm. ; length of arms unknown. One short, conical mouth papilla on 

 each side ; the infradental papilla) with inner end truncated and the abradial 

 corner a little produced. Mouth shield equally wide and long, with an 

 obtuse rounded angle within, inner sides curved, outer sides concave; side 

 corners and outer edge rounded. Side mouth shields meeting within, 

 broader without than within. 



First ventral plate small, elongated-hexagonal. Those beyond with 

 inner end truncated, outer edge concave, outer corners rounded, outer 

 laterals almost straight, inner re-enteringly curved. They are inconsider- 

 ably longer than wide. Side arm-plates with spine-ridge not very prom- 

 inent; the naked space which separates those of each two adjoining joints 

 is not seen from the dorsal side. Dorsal plates transversely oval, with an 

 indistinct angle within, about twice as broad as long. They are just in con- 

 tact in the inner part of the arm. 



The dorsal side of the disk is covered by delicate, rounded, overlapping 

 scales, among which the primary plates are not distinct. The radial shields 

 almost semilunar, as long as half the radius of the disk; they are in contact 

 in their outer half, their inner ends separated by a single row of scales. 

 Outside the radial shields is seen only one very narrow scale. The incisure 

 between the outer ends of the shields very small. Edge of the disk rounded, 

 the margin almost straight. Under side of the disk naked, except that there 

 is along the margin a band of scales, similar to those of the dorsal side. 

 Genital scales distinct at the inner end. 



w 



Three equally long, tapering, rather stout arm-spines, a little longer than 

 an arm-joint. One small, rounded tentacle scale at the inner corner of 

 the pores. 



Color in alcohol : pale brownish. 



One specimen from Station 3430, 852 £ 



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