EASTERN TROPICAL PACIFIC ASTEROIDEA. 83 
by me in 1913 (Bull. Amer. Mus. Nat. Hist., 32, p. 192). The number of adam- 
bulacrals in proportion to ten inferomarginals is either nine or ten, while the 
number of adambulacral spines is from six to eight, and there are from five to 
eight spines on the ventral surface of the plate. On the other hand the project- 
ing angle of the adambulacrals is not near the aboral end of the plate, but in 
the larger specimen is about at the middle and in the smaller is distinctly adoral. 
Probably these details of the adambulacral plates show considerable diversity 
in the species. 
The armature of thé superomarginal plates in the present specimens some- 
what resembles that of P. dissonus for from four to eight of the granules on the 
outer (lower) end of the superomarginals in the interbrachial are are more or less 
elongated into flattened, bluntly pointed spinelets. But these spinelets do not 
seem to be encased in ‘‘membranous sheaths” nor are they as long as in typical 
dissonus. 
Station 4654. Peru: off Aguja Point, 24 miles, 1,036fms. Bott. temp. 37.3°. Dk. br. m. 
Two specimens. 
Litonotaster tumidus,! sp. nov. 
Plate 3, fig. 3-6. 
R = 28 mm.; r= 14mm.; R=2r. Disk pentagonal, the arms arising 
quite abruptly from the angles. Br.= 6 mm. at base and nearly 2 mm. just 
before tip. In some specimens, the body is not noticeably pentagonal, the inter- 
brachial ares being very well-rounded. Thus in a specimen with R = 27 mm., 
r = 11.5 mm. and br., at the level of the interbrachial arcs, 11 mm., the form 
is quite evenly stellate. In all cases however, the disk is more or less swollen; 
in the holotype, the vertical diameter at center of disk is 11 mm. while at the 
margin the thickness is only 3.5 mm. 
Abactinal surface covered by numerous circular or rounded-polygonal, 
thin plates, .5-1 mm. in diameter, not very firmly united together and hence 
forming a flexible covering. In each interradius but one, is a circular plate, 
evidently larger than its neighbors, about 1.3 mm. across; in the fifth interradius 
is the madreporite, a somewhat tumid, rounded-triangular plate, 1.5 mm. 
across, adjoined on each of its three sides by a plate about 1 mm. wide and .75 
mm. high. Excepting the madreporite, these interradial plates are discernible 
only in dry specimens. In each radius, at the base of the arm, is a group of 
1tumidus = swollen, in reference to the flexible, puffed upper surface of disk. 
