﻿OI'IIIUTIIRIX DUMOSA. 



LIST OF SPECIMENS. 



169 



Locality. 



Whence obtained. 



109.5 

 1187 



lliiseuin of ComparcUive Zoology. 



12-(-| Panama. I I Alex. Agassiz. 



12-(- Panama. Dr. John LeConte. 



. . I Panama. | | Dr. Sternberg. 



Smithsonian Institution. 



Panama. 

 Panama. 

 Panama. 

 Panama. 

 Panama. 



West Coast Nicaragua Capt. Do 



Dr. Sternberg, 

 Uev. T. Powel 

 Dr. LeConte. 

 Mr. Edwardfi. 

 Mr. Akbin-st. 



I Alcoholic. 

 Dried. 

 Alcoholic. 



Alcoholic. 

 Dried. 



Ophiothrix dumosa Ltman. 



Ophiothrix dumosa Lvm.^n. Proceed. Boston Soe. Nat. Hist., VII. p. 252. 18C0. 



Special Marks. — Upper arm-spine longest. Spines on disk of sev- 

 eral sizes ; stout. Color dull blue. 



Descrijition of a Specimen. — Diameter of disk, 11.5°"°- ; from outer 

 side of mouth-shield to outer corner of opposite mouth-slit, 5""°' ; 

 width of arm without spines, 2.2"'°- ; length of arm, 72°""- ; distance 

 from outer side of mouth-shield to inner points of tooth-papilla3, to 

 that between outer corners of mouth-slits, 2.5 : 2.5. Teeth six, squarish, 

 thick ; cutting edge a little rounded, sometimes split in two ; upper one 

 rather narrower and more tapeiing. Tooth-papillge about thirtj^-eight, 

 arranged in two diverging, principal rows, between which are included 

 some smaller ones ; these two rows start, just below the teeth, with 

 a pair of large, flat papillae, like a tooth split in two ; these are followed 

 by a similar pair, after which the two rows diverge, growing smaller as 

 they pass lower down, and ending in papillee no larger than those which 

 serve to fill in the middle space ; in each of these principal rows there 

 are about nine papillae. The arrangement is the same in O. spicu- 

 lata. Mouth-shields oval heart-shaped, with a decided peak directed 

 inward ; length to breadth, 1.3 : 1.8. Side mouth-shields rather nar- 

 rower than is common in the genus, meeting within. Under arm-plates 

 much broader than long, hexagonal, with angles more or less rounded ; 

 first four plates smaller than those beyond, and much more rounded ; 

 most of the plates on the first third of the arm are hexagonal, with 



