98 University of Texas Bulletin 



the interradial arcs next to the disk paraboloid, sharply instead of broadly 

 curved, and in this respect more similar to Comptonia comptoni Forbes 

 than to C. elegans Gray. The two rows of supero-marginal plates are 

 apparently nowhere in contact throughout the length of the ray. Oral 

 and aboral sides of disk covered with rather small, unequal, polygonal to 

 rounded raised plates. 



ABORAL SIDE : The supero-marginal plates at the center of the arc 

 are slightly wedge-shaped with rounded interior margins ; their sides con- 

 verge slightly, passing out from the center of the disk. The plates de- 

 crease in size and are more elongate, on approaching the tip of the ray. 

 Over the central part of the arc seven plates have the breadth of about 

 10 mm. There are probably about 20 supero-marginal plates in one entire 

 arc (the tips of the rays are absent in the type) . 



Along the center of each ray is a row of radial plates which are larger 

 than the other central plates but not elevated above them. One elevated 

 rounded plate on each interray bears a small circular pore (gonopore). 

 In one interray there are two such plates. Between these plates are more 

 depressed rows of plates arranged so as to make a pentagon with its cor- 

 ners at the interradii. The central radial rows of plates along the rays 

 meet the middles of the sides of this pentagon. The small, raised, oval 

 madreporite is situated excentrically, and bears 9 or 10 radiating mostly 

 divaricate, V-shaped straight ridges. 



ORAL SIDE : The infero-marginal plates are equal in width and in num- 

 ber to the supero-marginal and lie opposite them or nearly so. The oral 

 surface of this starfish is distinctly broader than the aboral surface, so 

 that the line of junction of the two sets of marginals is situated well aboral 

 to the edge of the disk (and this does not seem to be due to crushing). 

 The infero-marginal plates are subquadrate-cuneiform in profile, but are 

 very thick and rounded at the external edge. No para-marerinal rows of 

 plates are visible. The other plates of the oral face of the disk, which 

 are poorly preserved, are also not in rows. The five ambulacral grooves 

 are distinct but without perceptible structure in our material. The num- 

 ber of rows of tube feet is unknown. The grooves are prominent, and 

 have near the peristome a breadth of about .6 mm. The marginal and 

 other larger plates are covered by rather fine, low, round, irregularly 

 scattered tubercles. Evidences of spine pits and pedicellariae are absent. 



The species differs from Comptonia elegans Gray in several noticeable 

 features. The disk is practically flat in our species; it however, shows 

 some evidence of flattening in preservation, since the central plates are 

 considerably and abruptly depressed below the level of the supero-marginal 



