ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS — FISHER. 83 



of a ray, forming a linear series. The genital stolon to which they are attached is 

 easily seen. Each duster is composed of a single tube divided at base into two or 

 three long branches, the latter being sub(ii\'ided into many, thick, irregular, often 

 grotesque side branchlets or pockets. Anal aperture present, connecting with a 

 large saccular intestinal coccum. Viewed from above this ccecum is shaped like a 

 butterfly with rounded wings, there being a deep sinus in the outline, in the inter- 

 radius to right of madreporic body, and anotlier shallower one in the left radius of 

 trivium (correspimding to anterior and posterior ends of butterfly). This carum 

 is connected with spacious stomach by good-sized intestine. Tiedemann organs 

 small; PoUan vesicles, one in each interradius. Tube feet pointed, without cal- 

 careous deposits; ampulla! double. Interradial septa membranous. 



Variations. — The principal variations have already been alluded to in the 

 foregoing description. These concern the number and relative thickness of paxillae 

 spinelcts; the relative size of the spinelets on upper edge of superomarginals, these 

 being usually smaller and two in number in northern specuiiens, frerjuently only 

 one in southern examples; the minute spinelets covering superomarginals, and the 

 number of pedicellaria', the former being thicker and the latter fewer in northern 

 examples, and more conspicuous in young than in very large specimens; the shape 

 of marginal spines, these being more often flattened and bifid in southern speci- 

 mens, and more often needle like in northern, the general appearance of actinal 

 spimdation, this varying from slender to papilliform, but never crowded; the 

 number of adambulacral spines and spinelets; mouth plates and their armature. 

 Some specimens have slightly wider and shorter rays than the type but the varia- 

 tion in this respect is inconsiderable. 



Young. — The smallest specunen, from station 292.3, has 11 = 31 mm., r = 7 mm., 

 and most of the adult characters well developed. The paxillie are fewer, but in pro- 

 jKirtion to size of specimen are larger than in adult. They have eight or ten spine- 

 lets, occasionally more. Marginal pedicellaria3 conspicuous; actinal intermediate 

 plates fewer than in adult. Tlie general appearance is unmistakable after one 

 knows the adult form, but the superomarginals encroach conspicuously onto to 

 abactinal area. The general facies of the marginals reminds one of Cheiraster, 

 except for the fact that the plates of the two series correspond. The abactinal 

 paxilliE and distribution of papulse are very different from Cheiraster. 



Tf/pe.— Cat. No. 22329, U.S.N.M. 



Type-localiiij. — Albatross station 4380, off Los Coronados Islands, southwest 

 of San Diego, California, 530 to 638 fathoms, gray sand, green mud. 



Distribution. — Washington to Lower Califoniia (Los Coronados Islands) and 

 from 277 to 822 fathoms. Usually on green mud or fine sand. 



