144 



THE OrillUElD^. 



the side plates thus not reaching the foregoing joint ; that naked space is 

 distinct also from the dorsal side. The side plates just meet above on 

 the inner joints, then are separated by the dorsal plates, and finally they 

 again meet in the outer part of the arm. Dorsal plates transversely oval, 

 with all sides rounded, scarcely separated on the inner joints, then in con- 

 tact almost to the end of the arm, where they again become separated ; 



about twice as broad as long. 



Disk covered by small but distinct overlapping scales, among which no 



The radial shields rather large, almost semi- 



primary plates are seen. 



lunar, pointed within, rounded without, twice as long as broad, their length 

 being' equal to half the radius of the disk. They are separated by some few, 

 irregdarly arranged, small scales ; sometimes they meet at their outer end. 

 Outside the radial shields is a narrow belt of scales in continuation of 

 those in the interbrachial space. Over the arm-basis there is a rather deep 

 but narrow incisure in the disk. Under side of the disk covered with smaller 

 yet distinct scales. Genital scale distinct only at the inner end of the geni- 

 tal slit. The margin of the disk re-enteringly curved ; the edge of the disk 



not sharp. 



Three, on the inner joints four, equal tapering arm-spines, a little longer 



than an 'arm-joint. Two small tentacle scales, which do not form a right 



angle with each other. 



Color in alcohol : gray, with a bluish tint. 



This species is very variable. Considering the described specimen as 

 the typical form, there can be distinguished no less than three rather con- 

 stant varieties : 



Vak. a (Plate VIII. Figs. 4, 5) differs from the typical form in the follow- 

 ino- respects. The mouth shield has the outer end more restricted, its whole 

 form being somewhat different (in other specimens, however, it has the same 

 shape as L the typical form). The ventral plates have the outer edge 

 strongly rounded, and there is a more distinct keel ; they are a little longer 

 than wide. The radial shields are narrower and separated by many snuill 

 scales, which are disposed in rather regular series. The scales on both sides 

 of the disk (except those around the radial shields) are very small, but high, 



The tentacle scales are smaller than in 

 the typical form; sometimes there are three. A specimen from Station 

 3424 has the mouth shields yet wider than in the typical form ; the scales 

 do not resemble grains, arc smooth, but as small as In the figured specimen. 



looking almost like small grains. 



^T 



