1913.] Clark, Echinoderms from Lower California. 207 



plates in each interradius, the most distal the largest; a very small plate on each side 

 of the first upper arm-plate, and two very small plates lying on each side of the radial 

 series, proximal to the radial shields; in the smaller specimen, these plates are all 

 relatively larger and are fully exposed; in addition, about forty other plates on the 

 disc are bare, but these are small and do not seem to be definitely arranged. Around 

 the dorsal genital slits, the granules are from a fourth to a third of a millimeter in 

 length and are thus quite spiniform. Upper arm plates at base of arm, wider than 

 long, tetragonal, in contact for their full width; they gradually become longer than 

 wide and broader distally than proximally, until at tip of arm they are triangular 

 and scarcely in contact. Interbrachial spaces below granulated distally but proxi- 

 mally the plates are simply bordered with minute grains. Genital slits very small; 

 first pan* (close to oral shield) is scarcely half the length of the first side-arm plate; 

 second pair about as long, situated transverse to the long axis of the arm, in an ele- 

 vation on the dorsal side of the disk, just distal to the radial shields. Oral shields 

 distinctly longer than wide, hexagonal with rounded angles in the type, but in the 

 smaller specimen more nearly triangular with a rounded, distal base. Adoral plates 

 rather short and wide, at sides of oral shields; they meet within in the smaller speci- 

 men, but are widely separated in the type. Oral plates large, two thirds as large as 

 adorals, bearing in the smaller specimen a few granules, which are much more 

 numerous in the type. Oral papillae, nine on a side; ninth (distalmost) longest but 

 very narrow; eighth largest, nearly as wide as long; inner ones successively narrower 

 and more pointed. No pores between basal under arm-plates. First under arm- 

 plate large, wider than long, roughly hexagonal; succeeding plates hexagonal, or 

 somewhat octagonal, with rounded angles, broadly in contact, wider than long on 

 basal third of arm but gradually becoming longer than wide and more pointed proxi- 

 mally, until at very tip of arm, they are triangular and well separated from each 

 other; the fifth or sixth plate is widest, measuring in the type, 2 mm. wide and about 

 1 mm. long. Side arm-plates large, but broadly separated both above and below 

 until near tip of arm; each plate carries on its distal margin, six (at middle of arm) 

 to eleven (eighth side arm-plate), short, flat, appressed spines; uppermost sharply 

 pointed, lower ones less noticeably so; third from bottom longest, about equal to 

 one half the length of the arm-joint. Tentacle-scales two, inner the larger; outer 

 does not overlap base of lowest arm-spine. Color (dried from alcohol) pale ashy- 

 gray above, finely mottled with black and cream-color; most upper arm-plates have 

 a light spot on their distal margin; arms faintly banded with blackish, some 15- 

 20 indistinct dark markings showing on each arm; lower surface pale cream-color; 

 smaller specimen like type, but a little darker. 



Type — Cat. No. , U. S. N. M. from Cape St. Lucas, L. C. 



Whether these specimens represent a new species or should be referred 

 to Ophiura daniana Verrill has been a source of much perplexity to me. 

 Through the kindness of Miss K. J. Bush, one of the type specimens of 

 Verrill's species was loaned me by the Peabody Museum and I have thus 

 been enabled to compare the specimens from Lower California directly 

 with one of those from Salvador. While the distance of fifteen hundred 

 miles between the two localities is not specially significant, I have concluded 

 that until specimens are known from the intervening coast, it will be quite 



