ASTBROIDEA OF NORTH PACIFIC AND ADJACENT WATERS — FISHER 



65 



are distinctly larger even in specimens half the size of the big examples of magister, 

 and have five or six median teeth in the vertical row in place of the usual four of 

 magister. These pedicellariae are about 0.3 to 0.35 mm. long. The larger sort are also 

 distinctly bigger, ranging in length of jaw, in the largest specimens, from 0.55 to 0.65 

 mm., the latter from the largest specimen, R 50 mm. (station 3347). Comparable 

 specimens of magister have the larger pedicellariae 0.37 0.45 If two approximately 

 equal-sized specimens are placed side by side the conspicuously larger pedicellariae of 

 the southern form can easily be seen with an ordinary glass. Specimens from the 

 southern extremity of the known range frequently have three or four unpaired 

 median teeth as against two or three in the Washington specimen, and two in most 

 examples of magister (but sometimes three). The madreporic body is small and near 

 the margin. 



Anatomical notes. — The gonads, similar in form to those of magister, have slender 

 branched lobes, and form a tuft which opens just under the inferomarginals at a con- 

 spicuous distance from the interbrachium — about 1.5 r, or about one-fifth of R. 

 This is much farther out relatively than the opening in magister. 



Young. — The young exhibit the same differences from the adult as characterize 

 magister, namely, the reduction of the actinal and dorsolateral regions. The plates 

 are consistently more delicate than in the young of magister (compare pi. 28, fig. 15 

 with pi. 28, fig. 2a) ; while the pedicellariae are larger. 



Type.— Cat. No. E. 1419, U.S.N.M. 



Type-locality. — Station 4335, off San Diego, Calif., 14 miles southwest Point 

 Loma Light, 500 to 530 fathoms, green mud, fine sand; bottom temperature, 39.5° F. 



Distribution. — From the vicinity of San Diego, Calif., to Washington (45° N. 

 lat.) in 284 to 530 fathoms, green and yellow mud or black sand. Temperature 

 range, 39.5° to 44.1° F. 



Specimens examined. — Twenty-three. 



Remarks.- — There are no specimens available between station 4243, the southern- 

 most record of magister, and station 3347, off Washington, the northernmost for 

 megalabis. Intergradation therefore has not been proved, but the southern form 

 seems to be quite evidently a deep-water representative of magister. 



It is noteworthy that while the major crossed pedicellariae of megalabis are 

 larger than those of magister, the reverse is true of the race from the sea of Japan. 



