1 86 



DISCOVERY REPORTS 



shoulders with them. In one specimen, from St. 190, the radials, costals and lower 

 brachials are raised into a keel-like ridge in the mid-line. The ossicles of the division 

 series and the brachials of the proximal part of the arm are narrower and less massive 

 than those of /. vivipara (Fig. 17 b). 



The side edges of the axillaries and lower brachials are sharp and straight. The 

 brachials are of the same shape, the positions of the first two syzygies are the same and 

 other syzygies are as numerous, as in /. vivipara. The distal edges of the outer brachials 

 are raised into moderately strong and conspicuous spines. 



Fig. 17. hornet ra graminea. a, cirrus, x 13. b, proximal part of a ray, x 13. c, disk, in which the anal 

 cone is broken and two of the ambulacral grooves imperfectly seen, x 11. d, z side- and a cover-plate of 

 a distal pinnule, x 66. 



The oral pinnules differ from those of /. vivipara and /. fiavescens, for P, is as stout 

 and as long as, or longer than, Pj , and P3 is longer than P2 . Pi and P, are of 8-10 segments 

 and 3-6 mm. long, depending on the size of the animal ; P3 is of 9-12 segments, 3-5-7mm. 

 long. The first three or four segments of Pi are attached by a web of tissue to the disk, 

 and the lower segments of Pa and P3 are similarly attached to the arm. The first genital 

 pinnule is P4 or P5, of about 10-12 segments; the last is P13 to P,6 , of about 15 seg- 

 ments and 7-9 mm. long. 



