470 



T^OF. P. M," DrNCAK OTT SOME 



The oral slits are large and wide ; the jaws are slender and 

 separate near the mouth-shield, and broader at the plate, where 

 the broad teeth are attached. These are four in number, and the 

 lowest has a re-entering curve to its free edge. There is a mouth- 

 papilla, long, lamellar, rather produced downwards on the edge of 

 the jaw close to the side mouth-shield ; and beneath the true teeth 

 there is a small broad lumpy papilla, somewhat resembling them, 

 but much smaller in size. 



There are five arms, which are about three or four times as long 

 as the diameter of the disk ; they are broad, and ringed with 

 dark grey and green colour, especially above. The lower arm- 

 plates are broader than long, broadest without, where there is a 

 slight rounding or nearly a straight edge, narrower, but still wide 

 within ; and the sides are either rounded, to give an elliptical ap- 

 pearance to the whole, or are straighter, slanting decidedly near 

 the oral edge of the plate. Towards the tip of the arm the shape 

 becomes hexagonal, and the outer edge is nearly straight and 

 broad, the inner being very short. 



The upper arm -plates, on mid arm, are nearly twice as broad as 

 long, overlapping, well rounded within, less so, or nearly straight- 

 edged without, the sides being sharply curved, the whole being 

 irregularly elliptical. At the tip they are longer and triangular, 

 with the point within. They form much of the upper surface, even 

 at the tip. 



The side arm -plates are large, extend on the top of the arm in 

 abroad process between the sides of the successiveupperarm-plates, 

 are flap-like, and stand out from the arm at the sides, and encroach 

 more or less short of separatiug the lower plates below. Some 

 have an accessory small spine at the edge of the plate above, to- 

 wards its end near the median line ; and all, except near the tip, 

 have four short, radiating, rather wide apart, blunt spines on the 

 edge. The lowest spine is the smallest, and the next is usually 

 blunter and larger than the others. There are three spines near 

 the tip. The longest spines are about the length of an arm-plate. 



The tentacle-scale, one on each side, is large, oftentimes nearly as 

 long as the lower arm -pi ate ; it is narrow where attached, and 

 broad and rounded slightly where free, and the length exceeds 

 the breadth. 



The diameter of the disk is ^ inch. The bands on the arm are 

 broad, and the dark grey-green tint occupies one ^r two upper 

 and side arm -plates j then there is the usual greenish-buff tint on 



