66 BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



A specimen from station 4427 and another from station 4334 contain each a 

 good sized parasitic Dendrogaster, probably D. arbusculus 19 as the general external 

 form is the same as in the type of that species. 



PEDICELLASTER MAGISTER ORIENTALIS. new subspecie x 



Plate 16, Figure 5; Plate 27, Figures 1, la-lc, 5; Plate 28, Figure 3; Plate 34, Figure 5 



Diagnosis. — Similar in general appearance to PediceUaster magister but differ- 

 ing in the following respects: Major crossed pedicellariae slightly smaller, with four 

 or five teeth in the median vertical series, instead of two; small ovoid straight pedi- 

 cellariae numerous on mouth plates; actinal plates fewer in each transverse series. 

 Rays slender, subterete, slightly swollen proximally, very gradually tapered to a 

 blunt point; disk small. R 52 mm., r 7 mm., R = 7.4 + r; breadth of ray at base, 

 7 or 8 mm. 



Description. — In alcoholic specimens: The surface is covered by small, spaced, 

 uniform, pulpy papillae — the spinelets — which are very inconspicuous, being 0.5 to 

 0.7 mm. long, interspersed with numerous sheathed pedicellariae that increase in 

 number and size on the sides and actinal surface. The papulae are small and not 

 easily distinguished. The surface of the rays has a soft, almost downy, appearance 

 owing to the small size of the spinelets and pedicellariae, and is much the same as in 

 alcoholic examples of magister. The furrow is bordered by a double row of pulpy 

 spinelets. 



The arrangement of the plates is essentially like that of magister, the dorsolaterals 

 and carinals being, if anything, a trifle broader lobed, but this feature is undoubtedly 

 variable. In a specimen with R 49 mm. there is a maximum of three actinal plates 

 to a transverse series in the median third of the ray. An equal-sized specimen of 

 megalabis has five or six plates to a series, and one of magister from station 4791 as 

 many as 10. It is perhaps a matter of age, rather than size, and I do not know 

 whether the smaller number in orientalis is constant. I think it probably is, as the 

 ray is more attenuate than in magister. 



In a dried specimen the abactinal spinelets, which are tipped by three to several 

 rather divergent hyaline points, reveal themselves in lines or groups of two, three, 

 four, and rarely five to a plate, the latter number occurring on the carinals. In the 

 type, however, the plates carry generally only one or two. The superomarginals 

 have one spine with sometimes one or rarely two smaller accessory spinelets, and the 

 actinals carry a single small spinelet. 



Adambulacral spines, two to a plate, similar to those of magister. The mouth 

 plates carry four or five slender spines, in a longitudinal, curved series, increasing 

 slightly in length from the inner to the outer. When there are five spines the two 

 outer form a transverse series. The mouth plates carry rather numerous, small, 

 straight pedicellariae, oval, blunt, and much smaller than in megalabis. (Compare 

 pi. 16, figs. 4 and 5.) 



The major crossed pedicellariae occur on the marginal and actinal plates very 

 abundantly; the smaller sort, on the abactinal and superomarginal plates, but not on 

 the actinal plates. The major variety are smaller on the average than in magister, 



'• Fisher, Bull. 76, U. S. Nat. Mus., 1911, p. 404, pi. 3, fig. 1. 



