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THE OPHIURIDiE. 



109 



f 



half so long. They are inserted close together at the side edge of the arm, 

 not at the outer edge of the side arm-plates. The three inner pairs of 

 tentacle pores with one wide and two small papilte at the distal edge; from 

 the fourth to the end of the arm there are two distinct elongated scales at 



the proximal edge. 



Color in alcohol : gray, with a bluish tint, arms white. 



39 specimens from Station 3402, 421 f ., most of them not well preserved. 

 Only imimportant variations to be noticed. 



This species is very closely related to 0. adspcrsiis Lym., perhaps really 

 the same species ; however, as with 0. semimidus and 0. valUncola, it seems 

 to us best to keep them separate for the present. There are only small dif- 

 ferences to be noticed. The mouth shield is a little different in form, and 

 the side mouth shields are separated within in 0. adspersiis, meeting in 0. 

 annectens. But there cannot be much weight given to this, as the mouth 

 region shows considerable variation in this genus. First ventral plate is 

 swollen in 0, adsjjersits^ not in 0, anncdens. The most important difference, 

 however, is found in the radial shields ; in 0, adsj^rsus their inner end is 

 covered with grains, in 0. anncdens they are quite naked, also their form 

 is somewhat different; and the radial shields are of importance as to the 

 specific differences in this genus. The arm-spines are somewhat longer in 0. 

 annectens than in 0. adspcrsiis ; the upper one about as long as a joint in the 

 former, only half that length in the latter. In other respects they are 

 entirely alike. It seems then quite possible to distinguish these two forms, 



but they are very closely related. 



It is interesting thus to find in the Pacific two species of OpUernus cor- 

 responding to the two Atlantic species. A third species from the Atlantic, 

 0, ahjjssalis, was described by Koehler (66) and further (67) recorded from 

 the Indian Ocean, where also 0. valUncola was found (Lyman). A third 

 species is also found in the Pacific, but this species and O. ahi/ssalis do not 

 seem to be closer related to each other, or to any of the other known species. 



7. Ophiernus polyporus n. sp, 



Plate V. Figs, 7-9. 



Diameter of disk, 14 mm. ; width of arm close to disk, 4.5 mm. ; length of 

 arms unknown, but certainly about as in 0. annectens. Ten (9-11) mouth 

 papillse on each side of the mouth angle ; the outer ones being really the 



