386 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



tinal intermediate plates, with 2 or 3 pores to each area. The 

 smaller example with R=:72 mm. has a few of these small areas at 

 the base of the ray. 



Type-locality. — Andaman Islands. 



Distribution. — ^Andaman Islands; Sulu Archipelago. 



Specimens examined. — Two : 



Station 5159, Tawi Tawi Group, Sulu Archipelago (off Tinakta 

 Island), 10 fathoms, coral sand; 1 specimen. 



Station 5163, Tawi Tawi Group (off Observation Island), 28 

 fathoms, coral sand ; 1 specimen. 



NARDOA TUMULOSA Fisher. 



Plate 95, fig. 9 ; plate 109, fig. 2 ; plate 111, fig. 2. 

 Nardoa tumulosa Fisher, 1917&, p. 90. 



Diagnosis. — In a general way resembling N. fHwnti Koehler in 

 having prominent, large, hemispherical, abactinal plates, but these 

 much fewer and relatively slightly larger than in frianti., lower in 

 proportion to width and evenly rounded or dome-shaped. They are 

 confined to the abactinal surface and the proximal tw-o-thirds of 

 ray ; plates of distal third of ray small, crowded, convex ; disk high. 

 E,=about 90 mm., r=about 14 mm. R=6.4 r ; breadth of ray at base, 

 17 mm. ; height of disk, 21 mm. 



Descinption. — The general form of this species, as well as the prin- 

 cipal differences between it and N . frianti are shown fairly well by 

 the figure. The prominent tubercles number about 10 to 15 on each 

 ray and are confined to the proximal two-thirds of the ray. Each 

 of these prominent plates is subcircular or elliptical (in which case 

 the long axis is transverse) and the edge of the plate is very slightly 

 and irregularly lobed, each lobe articulating with one of the irregu- 

 lar smaller and lower intermediate or secondary plates. The promi- 

 nent plates are dome-shaped and lower in proportion to the width 

 than are those of friamti. On the outer third of the ray the plates 

 are all small, rather strongly convex, and oriented longitudinally 

 (at least the more prominent ones, vv'hich are irregularly elliptical 

 in form). The abactinal granules are largest on the tuberosities,, 

 polygonal, and close-set, gradually diminishing in size toward the 

 papular areas, where they arc about half the diameter. The lower 

 convex plates also have the central granules enlarged. The papular 

 areas are smaller than the plates and in the type contain 15 to 30 

 pores, and in the smaller specimen only 6 to 10. 



The proximal marginal plates are not at all globular as are some 

 of the superomarginals in frianti^ but are slightly convex, and the 

 central granules are enlarged as in the case of the abactinal plates. 

 The last 10 or 12 plates of both series frequently have the central 

 granule enlarged into a definite thimble-shaped tubercle, or there 



