142 Bulletin Vanderbilt Marine Museum, Vol. VII 



narrow, tooth papillae. There are fifteen to sixteen tooth papillae 

 in each oval. 



The first under arm plate is much smaller and of somewhat 

 different shape than the others. It is pentagonal with the two 

 inner margins concave, convergent to a median apex, the side mar- 

 gins are moderately concave, adjacent to the angle of the side 

 mouth plate; the outer margin is nearly straight. The second 

 under arm plate is one and one-half times as long as the first and 

 has the inner and outer margins subparallel, straight, the outer 

 one being the longer ; the lateral margins are quite concave. The 

 third and succeeding arm plates are similar, the width being 

 1.6 times the length, each plate having the form of a subrectangle, 

 with the angles briefly rounded. There is one very large tentacle 

 pore present and but one scale which is small, oval, distally acute. 

 Near the disk, on some arms, the first one or two side arm 

 plates each bear four instead of three large arm spines ; farther 

 down each side plate bears three conical spines, the median of 

 which is the longest, being twenty percentum longer than the 

 upper spine and fifty percentum longer than the ventral spine. 

 Under magnification the spines are coarsely granulose, spinose, 

 especially along the lateral distal margin. Ventral to and in line 

 with the third spine is the true first ventral arm spine transposed 

 into a hook ; the peduncle is enlarged and bears a small scimitar- 

 like blade, which proximally on the concave side has two sharp 

 teeth and distally a curved blade. These hooks appear to increase 

 in size on the distal portion of the arm. Some have the second 

 hook nearly as large as the first. 



The dorsal arm plates are arched, having a median ridge longi- 

 tudinally. The inner and outer margins of each plate are sub- 

 parallel, the inner one being the shorter, while the lateral borders 

 are oblique. These plates are twice as wide on the distal margin 

 as long, and the proximal margin is 0.8 as wide as the distal. 



References : Ophiura marmorata, Lamarck, J. B., Anim. sans 



Vert., 1816, t. II, p. 543. 

 Ophiocnemis marmorata, MuLLER, J. and Troschel, F., System 



der Asteriden, 1842, p. 87.— Lyman, Th., Illus. Cat. Mus. X 



Comp. Zool., Harvard Univ., 1861, No. I, p. 152; Bull. Mus. 



Comp. Zool., vol. II, pt. 10, p. 234.— Duncan, P. M., Journ. 



Linn. Soc, 1884, vol. XXI, p. 103.— Doderlein, L., Zool. 



