136 



THE OPIIIUMDiE. 



First ventral plate very small, triangular, somewhat elongated. The 

 three next with the lateral sides a little restricted by the tentacle pores. 

 The outer edge of the second (and sometimes of the third also) a little re- 

 enteringly curved ; the other ventral plates have the outer edge gently 

 curved. From the fifth they are triangular ; they continue far out on the 

 arm, but are not distinct quite to the end. They are all about equally long 

 and broad, widely separated by the side arm-plates, which also meet broadly 

 above from the second (free) joint. Outer edge of the side arm-plates not 

 prominent^ the sides straight. The dorsal plates have an acute angle within 

 and outer edge very strongly produced, rounded ; a little longer than broad. 

 They continue to the end of the arm. At the base of the arm there are 

 four rudimentary dorsal plates, the inner one triangular, with angle inwards 

 (between outer ends of the radial shields), the two next four-sided, much 

 broader than long, the fourth five-sided^ with an angle without. At the 

 base of the arms, on each side of the rudimentary dorsal plates there is a 

 more or less developed granular covering, sometimes only some few grains. 

 The arms are very thin and flexible in their outer part. 



Disk covered with numerous rather delicate, small, smooth, angular (or 

 rounded) plates, among which the primary plates are usually not to be seen. 

 The radial shields are large and conspicuous, their outer ends more or less 

 broadly in contact, their inner ends separated by some few elongated scalcvS. 

 Their form is rather curious, the outer edge being bent strongly inwards and 

 very long ; the margin of the disk therefore bends inwards between the arms. 

 In the interbrachial spaces there is a rather large semilunar marginal 

 plate, separated from the radial shields by a little crescent-shaped plate on 

 each side. Under side of the disk also covered by small, polygonal plates, 

 somewhat larger than those on the dorsal side. The genital scales not dis- 

 tinct; the genital papilla) quite rudimentary; there are some a little more 

 distinct papilla? at the adradial side of the genital slit along the side arm- 

 plates. The genital slit reaches the margin of the disk. The edge of the 

 disk is rather sharp. 



Two or three short arm-vSpines, close together at the under side of the 

 arm ; the inner five or six free joints mostly bear only two spines ; beyond 

 them there are three. 



Three pairs of small round tentacle pores, each with one rounded tenta- 

 cle scale at the outer side. ... 



Color in alcohol : dark gray. . , 



'^' 



X 



