114 Bulletin, Vanderbilt Marine Museum, Vol. IV 



slightly greater than the width, in others the mouth-plate is very much 

 wider with the width 1.4 times the height. The side mouth-shields 

 are very narrow, with the outer end forming a wedge that fits between 

 the mouth-shield and arm-plate and extends to the margin of the 

 genital slit. The side mouth-plates are covered by the same type of 

 coarse, rounded granules that appear on the disk. The first under 

 arm-plate is smaller than the others and its inner margin fills the 

 angle of the mouth aperture. The second to eighth under arm-plates 

 are subquadrate with the outer margin convex, the inner one slightly 

 concave; the lateral margins concave. Near the tip of the arm these 

 plates appear fan-shaped. Tentacular scales two, the inner one oblong- 

 ovate, the outer one only two-thirds as long and broader, truncated 

 at the distal end; both conspicuous, oval, the inner fitting into the 

 concave margin on each side of the under arm-plate. The side arm- 

 plates are arched, nearly twice as wide as long, with the outer margin 

 a little convex, the inner nearly straight ; the arm-spines in series of 

 six to nine, about four-fifths as long as the supporting arm-plate and 

 extending for almost that distance upon the adjacent plates from the 

 second to eighth are each about twice as wide as long, with the inner 

 and outer margins relatively straight, the outer angles rounded. 

 Farther down toward the tip of the arm the inner margin of these 

 plates is distinctly shorter than the outer margin and the plates are 

 narrower. The dorsal arm-plates are wide. 



References: Ophiura appressa Say, Journ. Acad. Nat. Sci., Phila., 

 V, p. 151, 1825.— Lyman, Mem. Mus. Comp. Zool., I, p. 94, 1864. 



Ophioderma virescens Lutken, Add. ad Hist. Oph., pt. 2, p. 194, pi. 1, 

 figs. 4 a-4 d, 1859. 



Ophioderma appressum H. L. Clark, Mem. Mus. Comp. Zool., XXV, 

 p. 300, 1915. 



Ophioderma variegatum Lutken. 



Plate 67. 



Type: Lutken 's type came from Realego, Nicaragua, 5 fins., and is 

 deposited in the Copenhagen Museum. 



Distribution : San Diego, Calif. ; Lower California, Gulf of Lower 

 California, Costa Rica, Pearl Islands, Galapagos Islands. 



Material examined: Eight specimens, collected at Punta Arenas, 

 Costa Rica, February, 1928, Cat. no. 260. 



These establish the first record of the species from Costa Rica. 



Color: Variable. The disk is usually vivid green, occasionally 



