OPHITTEOIDEA FEOM THE ElOEEAN SEAS. 



475 



broader without than within, with sides sloping inwards. The 

 distal edge, wider than the other, is broadly curved, the convexity 

 pointing orally ; its angles are cut off and rounded ; there is a re- 

 entering curve at the sides, and the proximal edge is grooved, the 

 concavity looking orally. The plates are rather separate and 

 united by skin, and they are rather flat, and form the bulk of the 

 under surface. They are usually without any special tint other 

 than the light brown of the whole, but in some there is a pinkish 

 line on either side close to the edge. At the tip of the arm the 

 plates are longer, less iucised, and are closer together. 



The upper arm-plates are close, longer than broad, angular 

 orally, with a straight edge there, and they are boldly rounded 

 distally. They slope on either side from a median faint 

 central ridge, which ends at the rounded extremity in a faint 

 nodule. The sides slope to the angle, and are overlapped by the 

 side arm-plates, and one upper arm-plate slightly overlaps that 

 next to it. jSTear the tip the length of these arm-p)lates increases 

 over the breadth. A white longitudinal line with a red or purple 

 one on either side, of greater or less breadth, is often to be seen. 



The side arm-plates are well developed, and stand out from the 

 arm,formingwith the connecting-skin much of the side-arm. Below 

 the free edge extends outwards on a level with the surface of the 

 under arm-plates,and supports short spines and the small tentacle- 

 scale. Above, the inner end of the side arm-plate is prolonged 

 into a short angular process with a curved margin, which overlaps 

 and to a certain extent separates the upper arm-plates. This 

 process has one or more long spines on its surface, and the others 

 are on the free edge of the plate, where it forms the side of the arm. 

 The plates extend on the under surface of the arm, but do not 

 meet, and are broad enough to place the tentacle-scale well with- 

 out. The scale is small, largest at the base, and minutely thorned. 



The spines near the disk are numerous, and they vary from 9 to 

 12 ; further on they diminish to 7, 5, and 3 in number. 



The spine next to the tentacle-scale is the smallest, and is a 

 mere spinule, with a sharp thorn on the plates nearest the disk and 

 for some distance, but soon the thorn becomes bent and a second 

 one forms on its side, and there is a boss-like prominence below 

 and near the origin. This two-toothed and curved hook increases 

 in size towards the end of the arm, is glassy, and points orally. 

 Sometimes there are three teeth. The next spine is slightly 

 larger, is flat, tapering, serrated and striated, and often bushy at 



