42 OPHIOGLYPHA SARSII. 



middle line of arm, and meeting to fonn the outer and inner points of 

 the plate ; and two short laterals. Side arm-plates have a large pro- 

 portionate size to that of other plates ; where they meet below, the line 

 of juncture is straight, and this line grows longer as the plates encroach 

 more and more ; thus its length, to that of corresponding imder arm- 

 plate, is as follows : first joint, .4:1; twentieth joint, .8 : .6 ; about two 

 thhds out on arm, .8 : .4 ; the upper side of each side arm-plate runs 

 outwards and downwards in a curved line, and overlaps the correspond- 

 ing upper arm-plate ; the outer side runs almost straight do^vnwards to 

 the tentacle-scales, where it makes a little point, and then bends inwards 

 to meet its corresponding plate on the middle line of the arm ; the side 

 arm-plates do not meet above till very near the end of the arm. Upper 

 arm-plates, at base of arm, longer than broad, outer side slightly curved, 

 and longer than inner side, so that the lateral sides are sloping ; farther 

 out the plates grow proportionately longer, and their outer sides more 

 curved ; plates near tip of arm long heart-shaped, the point imvard ; 

 nearly four plates are included in the incision of the disk ; first plate 

 small, triangular, thickened, its point being directed inword, length to 

 breadth, .8 : .8 ; second plate also small, four-sided, outer side longer, 

 length to breadth, .8:1; third plate proportionately wider than second, 

 length to breadth, .8 : 1.4 ; fourth plate, .8 : 2.2 ; fifth plate, 1:3; sixth 

 plate, 1 : 2.8 ; length of inner side, 2™™- ; about two thirds out on arm, 

 1.2 : 1 ; close to tip of arm, .6 : .4. Disk, above: radial 

 shields large, bounded, and more or less overlapped, 

 along their edges, by surrounding scales ; the outer 

 half of their inside edge is free, and bounds the inner 

 portion of the incision in the disk, its outer portion 

 being bounded by radial scales ; length to breadth, 

 3.2 : 2.2 ; in centre of disk six large, romided, nearly 

 equal primary plates, central one nearly round, others oi.hio-i.vpi sar^i. 

 somewhat oval, their edo-es overlapped l^v finer scales ^'i^f " ^'[Jf- siio«in{r the oomb 



' o i i . ol |);i]>ill;e at tlic I'iise of the 



about them; diameter of centre plate, ISr^^-; in mter- =*''"■ ^. "pp^.' arm-piate. 

 brachial spaces, between central primary plates and edge of disk, three 

 other primary plates, lying in a line at about equal distances ; mner one 

 rounded, middle one long oval, outer one, lying on the \QYy edge of disk, 

 rounded ; in brachial spaces, one rounded primary plate, lying close to 

 inner ends of radial shields ; space between radial shields filled by a 

 very small scale, l3'ing outside, followed b}" a large scale, and this by 

 two or three very small scales irregularly disposed ; rest of disk, above, 

 covered by numerous irregular scales, some as large as primary plates, 

 but most of them varj'ing in length from .4"'™" to 1""' ; disk, below, cov- 

 ered closely with more regular and even scales than those above ; near 

 the mouth-shields, in particular, they are of even size, and, are regularly 

 iml^ricated, having an average length of about .8™™'. Genital slits edged 



