110 



THE OPHIURIDiE 



scales of the second mouth tentacle ; the inner ones are pointed, conical, the 

 outer rounded; usually two, sometimes only one at the apex, below the long 

 club-shaped teeth, which are four or five in number. Mouth shield triangular, 

 with outer end restricted, looking like a short stalk; corners rounded; a 

 little longer than broad. Side mouth shields much broader without than 

 within, where they meet. 



First ventral plate indistinct, those beyond a little longer than wide, with 

 outer edge curved and inner end truncated. The lateral sides much re- 

 stricted : the outer part by the tentacle pores, the inner part by another pair of 

 pores, which give the ventral side of the arm a very curious appearance. By 

 these two pairs of pores to each joint the ventral plates are so restricted as to 

 appear like a narrow median band along the under side of the arm. Farther 

 out on the arm these pores become smaller, and from about the middle of the 

 arm they wholly disappear. The side arm-plates do not meet either below 

 or above ; they are very wide, with outer edge sharp, finely curved in out- 

 line. From the tentacle pore to the margin of the arm there is a slight 



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elevation, parallel to the outer edge of the plate. At the outer end of this 

 elevation the arm-spines are inserted. The dorsal plates are more than twice 

 as long as broad, with outer edge a little wider than inner edge, both 



slightly curved; lateral sides straight. They have a feeble keel. The 

 4hree or four inner ones more or less rudimentary, with a naked space on each 

 side. The arms are very wide, flat, triangular in section ; their under side 

 is deeply hollowed in the median line in the inner part, farther out it is flat. 

 The joints enclosed in the disk are considerably narrower than those outside 

 the disk ; farther out the arm gradually becomes narrower again. 



The dorsal side of tlie disk is covered almost wholly by the large naked 

 radial shields, which are as long as three fourths of the radius of the disk; 

 the little central space is covered with a close granulation, beneath which no 

 scales are seen. The radial shields are in contact in their whole length, or 

 partly separated by a row of very small scales; in the interbrachial spaces 

 they also are in contact, only sometimes separated by a narrow line of 

 granuloe. Their abradial margin is covered with some indistinct scales, 



The outer edge is doubly curved, 

 and the outer corner is somewhat produced outwards. Outside that there 

 are again some mostly naked scales; the disk is thus considerably produced 

 in each interbrachial space. Under side of the disk covered along the margin 

 and the genital slits with very indistinct small scales; in the middle part 



w^hich are again covered with granulse. 



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