"n- x-r 



THE OPIIIUmD.E. 



183 



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a five-sided naked space. They have a truncated angle within and a deep 

 cut in the outer edge, thus bifurcating at the outer end; inner and outer 

 laterals slightly concave. They are broader than long. Sometimes the 

 inner end of the ventral plate is divided from the chief part of the plate. 

 Side arm-plates with spine-ridge little prominent. Dorsal plates rhomboidal, 

 twice as broad as long, in narrow mutual contact in the whole length of the 

 arm ; inner sides slightly concave, outer edge convex in the middle, concave 

 towards the sides. (In fact, the dorsal plates are closely soldered with the 

 arm-bones, and mostly consist of small, irregular, ill defined plates, whicK 

 look like a single plate.) The plates are distinct only in dried specimens. 



The disk is wholly naked,* except the radial shields and a single row of 

 scales all round the margin ; between the radial shields there are 4-5 ; in 

 the interbrachial spaces there are about 15 or more, the number being rather 

 variable. The radial shields are club-shaped, with a little interbrachial pro- 

 lono-ation at the outer end; they are one fourth as long as the radius of the 

 disk. Along the genital slits also is seen a row of overlapping scales, more 



or less distinct. 



Four or five short, stout arm-spines, about as long as an arm-joint^ the 



upper one the longest. No tentacle scale. 

 Color in alcohol : pale brown. 

 Several specimens from Station 3397, 85 f., and from Panama. 



61. Sigsbeia lineata n. sp. 



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Plate XX. Figs. 5-8- 



Diameter of disk, 7 mm, ; width of arms close to disk, 2.5 mm. ; length of 

 arms about five times the diameter of the disk. (The rolling up of the arms 

 makes the measuring somewhat inaccurate.) Four (three) mouth papilla) to 

 each side of mouth angle, and one diamond-shaped at the apex; they are 

 short and square, making a close line. That on the apex sometimes is 

 separated from the oral pieces, the two papilloo at its sides joining in the 

 median Une (Fig. 5). Mouth shield semilunar, with a very little peak 

 within and outer edge curved, sometimes a little restricted at the sides by 

 the genital slits, but not with a peak without- it is much broader than long. 



* Sometimes there are, however, some spread, irregular scales in the disk skin, seen only in dried 

 specimens. 



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