' V-^-, Hrt 



r 



1^ 



-.^jsfpyip- 



-^. M ' ' 





^^JV" "^^ /j -■-^■•^ "iyi-i"" J^' "^^ ''^ ■■f' , , rf^fV. T^- - l-^-IN-X - _'■ 



->■ -JV 



-I \l ^ r''J^J\ -^^ ' 



-■ ' 7*-7 J.-rfA' 



■^T^ 



^ 



THE OPHIURJDiE. 



123 



most square, the innermost pointed ; one a little larger on the apex of jaw. 

 Moutli shield with an angle within^ outer edge almost straight, outer corners 

 rounded ; the lateral sides are a little restricted by the genital slits ; equfilly 

 broad and long. Side mouth shields long and narrow, meeting within. 



First ventral plate polygonal^ as large as the foUoAving. Second to fourth 

 (third) with inner end truncated, those farther out with an angle within; 



r 



from the fifth (fourth) they are widely separated. Outer edge of the first 

 three ventral plates much rounded, then it gradually becomes almost 

 straight. Outer laterals straight (along the tentacle pores), inner laterals 

 re-enteringly curved. Side arm-plates long and almost straight, meeting 

 broadly below from the fourth joint, above from the fifth to sixth joint. 

 Dorsal plates with outer edge much rounded, inner end truncated on the 

 first 5-6 joints 5 from here they have an acute angle within, and are sepa- 

 rated by the side arm-plates ; the lateral sides are straight. 



The disk is covered with coarser or finer overlapping scales, among 

 which the ]3rimary plates are rather conspicuous, especially because they 

 are of a darker color than the other scales; the network of the chalk sub- 

 stance is coarser than in the other scales. Radial shields not very large, 

 separated within by one or more scales, meeting more or less broadly with- 

 out, the one overlapping the other. Sometimes they are wholly separated 

 (Fig. 2). Outer edge of the radial shields rather straight, there being 

 almost no incisure at all in the disk at the base of the arm. In the inter- 



brachial spaces there is usually an inconspicuous marginal plate. Ventral 

 side of the disk covered with similar overlapping scales, among which none 

 are conspicuous. Genital plate narrow, becoming a little broader as it 

 passes to the dorsal side of the arm, where it bears the arm-comb, whose 

 two parts almost or wholly meet in the median line over the arm-basis. The 



r 



papilla) are rather short, more or less pointed, 6-9 to be seen from above. 

 There is no secondary arm-comb. Papillae along the genital slits small, close 

 set, rounded. The dorsal side of the disk flat, the margin not rounding 

 towards the ventral side^ whereas the ventral side bends towards the dorsal 

 side. There is, however, no sharp edge. 



Three rather well developed arm-spines, the upper one the longest, the 

 lowest one the shortest; especially on the first free arm-joints the upper- 

 most spine is long, almost as long as the next joint ; they are not quite 

 equally spaced, the uppermost being a little apart from the other two. The 

 tentacle pores are distinct in the greater part of the arm; the first pore 



