108 Proceedings of the Biological Society of Washington. 



similar to P3 but with the segments, especially the distal, proportionately 

 shorter. P5 is 6 mm. long with sixteen segments of which the outer 

 become greatly elongated, and the third and following have prominently 

 everted and spinous distal edges. The following pinnules resemble P5, 

 but gradually increase in length so that the distal pinnules are 8 mm. 

 long, composed of seventeen segments most of which are about twice as 

 long as broad, with produced and spinous distal edges; the two terminal 

 segments of the distal pinnules are rather abruptly smaller and more 

 slender than the preceding. 



The color is purple, the cirri yellow, each segment with a median 

 ventral purple saddle; regenerated arms are yellow. 



Type.— Cat. No. 35,631 U. S. N. M., collected by Mr. Alan Owston in 

 Sagami Bay, Japan, in 55 fathoms. 



Prometra owstoni is most nearly related to P. longipinna A. H. Clark 

 from the Philippine Islands in 58 fathoms. 



