424 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



of the disk is occupied by some smaller, but unequal, imbricated 

 plates, with the distal border rounded. The radial shields are of 

 the same size as the primary radials; they are triangular, with 

 rounded angles, as long as broad, and their length equals one-fourth 

 the radius of the disk. The two shields of each pair are rather 

 divergent, and they are separated for their whole length by a row 

 of plates, though outwardly they come close together; in one of 

 the radii they are even in contact for a short part of their length. 

 (The shape of the plates found at the periphery of the disk, such as 

 the radial shields or the large interradial plate can not be judged 

 from the photograph which I give in figure 7, for, because of the 

 strong convexity of the disk, the peripheral plates, seen fore- 

 shortened, are rather strongly distorted and their length is con- 

 siderably diminished.) 



OPHIOZONELLA MEDIA (Koehler). 



Plate 78, figs. 9-10. 



Ophiozona depressa, var. media KCEHLER ('04), p. 24, pi. 4, figs. 11, 12. 

 Ophiozonella depressa, var. media MATSUMOTO ('17), p. 294. 



Locality. Albatross station 5601; Gulf of Tomini, Celebes; Limbe 

 Island (NE.) bearing N. 38.36 kilometers (20.7 miles) distant (lat. 

 1 13' 10" N., long. 125 17' 05" E.) ; 1,399 meters (765 fathoms) ; 

 November 13, 1909; S., Glob., Ptr. 



One'specimen (Cat. No. 41355, U.S.N.M.). 



Notes. The diameter of the disk is 11 mm. 



This specimen agrees well with some individuals collected by the 

 Siboga in the Sunda Archipelago, which I considered as represent- 

 ing a simple variety of 0. depressa Lyman; I described this in 1904 

 under the name of O. depressa, var. media. But in comparing the 

 Albatross specimen with the description and the figures which Lyman 

 gives of O. depressa it seemed to me that the form from the Sunda 

 Islands and from Celebes differed decidedly too much from Lyman's 

 type to make it possible to consider it as a simple variety, and 1 

 propose to raise it to specific rank, giving it the name of Ophiozonella 

 media. The Albatross specimen is of exactly the same size as Ly- 

 man's 0. depressa, and as this is the case the differences may be 

 apreciated more readily. 



If we compare the photographs which I give here (pi. 78, figs. 

 9, 10) with the figures which Lyman has given of 0. depressa ('82, 

 pi. 2, figs. 16-18) we see that the dorsal plates of the disk are more 

 numerous in O. media, and especially that the plates of the central 

 rosette do not have that tuberosity described by Lyman (and which 

 also does not occure in the Siboga specimens). The mouth shields 

 are less elongated and broader, and in the Albatross specimen they 



