134 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



than in hahrogenys and are not tumid. The lateral inferomarginal 

 comb is reduced to a long, fine spine and 1 or 2 similar but smaller 

 ones are vertically below it ; furrow comb, 6 to 8 spines ; no pedicel- 

 lariae. In habrogenys the lowest lateral spine is the longest. 



PERSEPHONASTER MONOSTOECHUS Fisher. 



Plate 20, fig. 2; plate 21, fig. 2; plate 31, fig. 5; plate 37, figs. 3a-e. 

 Persephonaster monostoechus Fisher, 1913a, p. 620. 



Diagnosis. — Related to P. croceus Alcock and Wood-Mason, which 

 it resembles in having, in addition to the appressed inferomarginal 

 spines, a conical erect lateral spine, but differs in having only 1 series 

 of erect superomarginal spines (peculiarh^ situated), narrower mar- 

 ginals, 8 furrow spines, small actinal interradial areas, and irregu- 

 larlj'^ occurring and smaller, erect, lateral spines. R=45 mm., r=8.5 

 mm., E=5.3 r; breadth of ray at base, 12 mm. Eays rather slender, 

 with, proximally, high lateral walls sloping steeply but not quite 

 perpendicularly; marginal plates massive, tumid, the superomar- 

 ginals encroaching conspicuously upon the aliactinal surface bej^^ond 

 the base of ra}^ Interbrachial angle abruptly rounded. 



Description. — Paxillar area narrow, being about as wide at the 

 base of ray as the length of the first superomarginals. Paxillae com- 

 paratively large, though the number of spinelets is not great. Pax- 

 illae largest in the interradial regions and adjacent portions of ray. 

 The base of the stout tabulum is roundish on the disk, with slight 

 indentations, but on the ray the plate as well as 'the section of tabulum 

 is elongate elliptical and the tabulum or pedicel becomes lower and 

 lower on the outer part of the ray until the plates are merely slightly 

 convex. A large interradial paxilla has 15 to 18 pointed slender 

 spinelets about as long as the convex tabulum, 3 to 5 occupying the 

 center. In the center of disk, where the paxillae are small and the 

 pedicels are slender instead of thick, there are 5 to 10 slender spine- 

 lets. The large paxillae extend far along ray on either side, but are 

 compressed instead of round. On the radial region of each ray are 

 several large fasciculate pedicellariae, sometimes broader than pax- 

 illae, composed of 4 to 8 pointed tapering spinelets, much stouter 

 than those of paxillae, and springing from low plates resembling 

 reduced paxillae. 



Superomarginal plates, 28 in number, are fairly large and tumid, 

 the first 4 or 5 being confined to the side wall of the ray and bearing 

 their single upright conical spine practicall}' on the upper edge of 

 the plate; but with the fifth plate the spine recedes from the inner 

 edge, and more and more of the surface of the plate is abactinal. 

 With the eighth or ninth plate the 2 facets are about equal, but 

 distally from this point the dorsal becomes much the wider, and the 



