68 



OPHIOPLOCUS. 



the ami-joints. Tentacle-scales two, lying obliquely, and fomiing to- 

 gether a very regular oval. Color, in alcohol : white, with a few light- 

 grayish bars on the arms, and cloudings of the same tint on the disk. 



Variations. — The above description was taken from a young speci- 

 men. Accordhig to Dr. Liitken, the adult has a disk of 10°""", and arms 

 of 30 or 40°™\ There are five arm-spines also. 



O.-padfiaa has been found at Puntarenas (Dr. Orsted) in one fathom 

 water, and at Panama (Alex. E. R x\gassiz). It differs from 0. hnpressa 

 in the smallness and regularity of the arm-spines. 



LIST OF SPECIMENS. 



OPHIOPLOCUS* Lyman. 



Disk closely and finely scaled above and below. Genital scales 

 hidden. Teeth. No tooth-papillre. Mouth-papilloe. Side mouth- 

 shields wide, and nearly, or quite, meeting within. Arm-spines ar- 

 ranged along the outer edge of the side arm-plates. LTpper arm-plates 

 di\ided on the middle fine into halves, which at the base of the arm 

 are placed at the outer lower comer of the joint, on each side being 

 separated by a number of supplementary pieces. At the tip of the 

 arm the plate is simple ; then it divides in two, and the halves are 

 gradually forced apart by the intrusion of supplementary pieces. Two 

 short genital slits, extending only half-way to the margin of the disk, 

 and beginning outside the mouth-shields. 



* "O^ts, snake ; 7rXo<or, a twisted rope. 



