ASTEROIDEA OP NORTH PACIFIC AND ADJACENT WATERS — FISHER 83 



the plates are separated about as widely, but in another (station 4427), a trifle larger, 

 the symphysis is much narrower than the length of the first plate. I think there is 

 a tendency for the northern specimens to have a slightly narrower symphysis than the 

 southern. The structure of the first pair of adambulacral plates is of interest here, 

 because in PediceUaster and close allies (having five or six rays) the first adnmbulacrals 

 are not in contact back of the mouth plates, whereas in the Asteriinac one pair at 

 least, usually several, are in contact, forming the so-called adoral carina. In this 

 species we really find a transition between the two types of structure. 



The fairly large mouth plates carry, on the actinostomial margin, either one or 

 two acicular spines and a straight pedicellaria with usually two teeth to the jaw. 

 On the surface are one or two spines similar to the adambulacrals, and sometimes 

 a pedicellaria. There may be, thus, two to four spines on each plate. (PI. 31, 

 figs. 2, 2a.) 



The crossed pedicellariae are scattered on the skeletal meshes and are rather 

 lacking in striking features. In profile the vertical series of teeth show usually about 

 six or seven rather irregular dentations. Length, 0.32 to 0.36 mm. (PI. 31, figs. 2b, 

 2c.) The pedicellariae of Ludwig's types agree in size and detail. The straight 

 pedicellariae are of the narrow-spatulate, unguiculate type with generally two to 

 four small curved teeth to each jaw tip. (PI. 31, figs. 2d, 2e.) They are scattered 

 over the surface of tho body and along the furrow margin from the inner end of the 

 oral plate to the end of the ray. The abactinal show greatest diversity in size and 

 form and usually have four teeth; the furrow pedicellariae are relatively less spatu- 

 late, with two or three teeth, as a rule (0.9 to 1.25 mm.). 



The furrow is broad (0.5 r), with rather crowded, four-ranked, tube-feet, which 

 only at the end of the ray become two-ranked. The ambulacral pores are not at all 

 in straight but in two distinctly zigzag series, which straighten out only at the end 

 of the ray when the furrow narrows. 



Madreporic body small, near the margin, and surrounded by a circle of spinelets. 



Anatomical notes. — The gonads open dorsally near the upper margin of the 

 second superomarginal plate (in the one specimen dissected). The ovary consists 

 of four or five elongate lobes; eggs large. Stomach spacious, without distinct dorsal 

 and ventral parts; coecum large, sac-like. Ampullae large, not bilobed. No Polian 

 vesicles. 



Type— Cat. No. 34407, U.S.N.M. 



Type-locality. — Station 3425, near Tres Marias Islands, Mexico, 21° 19' N., 

 106° 24' W.; 676 fathoms, gray sand; bottom temperature, 39° F. 



Distribution. — From the Tres Marias Islands, Mexico, to Washington (47° 29' 

 30" N.), 277 to 676 fathoms; temperature range, 37.9° to 42.8° F. 



Specimens examined. — Thirteen. 



