124 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. . 



central superomarginal spine, forming a single longitudinal series 

 along ray (not 2 conical robust ones, forming 2 parallel series along 

 ray) ; more numerous furrow spines. Disk larger than in either 

 cingulatus or roulei. R=110+nim. (tip of ray broken), r=24 mm., 

 Ezi=4.6+r; breadth of ray at base 28 mm. Interbrachia open; rays 

 tapering very gradually ; height of ray at base less in proportion to 

 width than in cingulatus or patagiatus. 



Description. — Marginal plates massive, tumid, the superior series 

 encroaching markedly upon paxillar area ; the latter narrow on rays, 

 beyond the middle being about as wide as a corresponding supero- 

 marginal. Paxillae small, with a low pedicel surmounted by a flat- 

 topped group of terete, blunt spinelets as long, or slightly longer 

 than height of tabulum. Largest paxillae, at base of rays and on 

 disk at middle of r, with about a dozen peripheral and 5 to 7 central 

 spinelets. Far along ray the spinelets are much higher than tabulum 

 and as few as 2 or 3, more often 5 to 8 in a coordinate group. 

 Scattered over the paxillar area are fairly numerous plates without a 

 perceptible tabulum and with 2 to 10 tapering, pointed spinelets, 

 markedly stouter than those of the regular paxillae, and forming 

 fasciculate or fasciculate-pectinate pedicellariae. Plates interme- 

 diate between these and the normal paxillae are observable. Some- 

 times the spines form two opposed rows, sometimes are grouped in a 

 circle. 



Superomarginals over 40, shaped as in P. cingulatus^ the median 

 transverse line being covered with scalelike granules, the slopes on 

 either side with tiny terete spinelets. Near middle of plate are one 

 or 2 slender appressed, sharp, flattened spinules not as long as the 

 plate (absent from 6 or 7 interbrachial plates). Each plate also has 

 several inconspicuous fasciculate pedicellariae, modified from both 

 the slender and the scalelike spinelets, and occurring on both upper 

 and lateral faces of plate. 



Inferomarginals corresponding to superomarginals in number and 

 position, tumid and encroaching upon actinal area about as much as 

 in cingulatus. Proximally the plates bear a lateral oblique comb of 

 3 or 4 slender, flat, sharp, appressed spines, about the same length as 

 in cingulatus (but fewer). The general covering of the plates con- 

 sists of squamiform granules, or spinelets, becoming more spiniform 

 on the margins. There is also a fasciculate spiniform pedicellaria 

 near the upper margin of most of the plates. 



Actinal interradial areas small; the first series of intermediate 

 plates extending to the eighteenth inferomarginal, or half the length 

 of ray, the outer plates being small and rudimentary ; the second series 

 to the sixth plate; the third series to the third plate, while in the 

 first interradial series between mouth and first inferomarginal plates 



