48 THE VOYAGE OF H.M.S. CHALLENGER. 



rliomboidal, broad without and with a blunt angle inward, separated their entire length 

 by a wedge of larger and smaller disk scales; length to breadth 2:1. Interbrachial 

 surface on the under side covered with the same fine overlapping scales as above. 

 Genital scales small, narrow within, widening a little without as they appear above the 

 disk. Along their free edge, which extends from outer edge of mouth shield to margin 

 of disk, there is a close row of minute, squarish, tooth-like papUlse, which become short 

 and rounded on the arm comb. Three small pointed arm spines, situated low on the 

 edge of the side arm plate close to the tentacle scales. On the pores of the mouth 

 tentacles five large rounded scales similar to the mouth papillse, on either side ; on the 

 second set six on the interbrachial side and four on the brachial ; immediately beyond 

 the disk there are only one or two on the inner and none on the outer side. Colour in 

 alcohol, white. 



Station 143.— December 19, 1873 ; lat. 86° 48' S., long. 19° 24' E. ; 1900 fathoms ; 

 globigerina ooze. Station 164a.— June 13, 1874 ; lat. 34° 13' S., long. 151° 38' E. ; (young 

 of this species ?) ; 410 fathoms ; grey ooze. 



Opiiioglypha orbiculata, Lym. (PI. VIII. figs. 10-12). 



Ophioglypha orhkulata, Lym., Bull. Mus. Comp. Zool., vol. v., part 7, p. 74, pi. iv. figs. 

 103-105, 1878. 



Three very short, small, sharp arm spines, low down. Mouth shield as broad as long. 

 Eadial shields short, rounded, and separated by the fine scaling of the disk. PapUlEe of 

 arm comb close set, flat, and with rounded ends. 



(Type specimen from Station 237.) Diameter of disk 15*5 mm. Width of arm close 

 to disk 27 mm. Six or seven mouth papillse on each side, small, irregular, and tooth-like, 

 with three longer and more pointed at apex of jaw. Mouth shield broader than long, five 

 sided, having a broad angle within, with outer lateral corners rounded ; length to breadth 

 2*5 : 2*3 Side mouth shields, following inner angle of mouth shield, narrow, pointed with- 

 out, and broader within, where they meet. First under arm plate transverse oval, broader 

 than long, often with lateral ends pointed ; second arm plate four sided, with corners much 

 rounded ; the next three are pentagonal, with an angle inward, and outer edge curved ; 

 beyond these the lateral sides become shorter, so that soon the form changes to very wide 

 triangular, with a broad curved outer edge, and an ol^tuse angle inward. Side arm plates 

 broad, little swollen, meeting below beyond the disk, separated above by upper arm plates, 

 of which the first is oval, with pointed lateral ends ; those beyond four sided, broader 

 without than within, outer side curved, lateral sides nearly straight. Disk flat, smooth, 

 and very thin ; upper surface covered with small, irregular, closely overlapping scales, 

 with a row of larger scales along the margin. Piadial shields broad triangular, with edges 

 rounded, separated widely by a group of disk scales ; length to breadth 2*3 : 2. On the 

 under surface the scales are more uniform, and are arranged in irregular transverse rows, 

 four to six in each row. The genital plate, except at its outer end, appears only as a 



