OPHIUROIDEA OF THE BAHAMA EXPEDITION. 53 



truncate; sometimes the more distal is the larger, and some- 

 times the one next the distal. The three or four inner ones 

 form a close row; they are rather slender conical, or com- 

 pressed, acute. The tooth-papillae (exclusive of the granules 

 near them) seem to be ordinarily but three or four; in one 

 case, perhaps, five; of these, two are usually above the rest, 

 inside the mouth, and not visible from below. They are all 

 small, conical, and variable in form. In Mr. Lyman's de- 

 scription, the jaw-granulations are probably confounded 

 with the true tooth-papillee, for he gives a large number; — "a 

 cluster of a dozen." At the distal angles of the mouth-slits 

 there is. on each side, a vertical, flat process, looking like a 

 small mouth-papilla from below, but it extends far up into 

 the slit and bears a spiniform papilla at the side of the inner 

 oral tentacle. Its outer end is rounded and forms the distal 

 boundary of the outer oral tentacle-pore; it does not seem to 

 be movable, and arises at the suture of the adoral shield and 

 first arm-plate, but seems to be attached more to the adoral 

 plate.* 



The first under arm-plate is small and concave. Four or 

 five basal ones are scarcely separated by the side plates; they 

 are about as long as broad, with an obtuse proximal angle; 

 the distal end is prominent and strongly convex; farther out 

 they become more nearly rhombic, with a distinct, obtuse, 

 distal angle, and are then more separated. 



The outer oral tentacles are very large and reach to the 

 center of the mouth; they are not retracted, but have dried 

 fully extended, as if they were more or less stiffened, in our 

 specimen. Their pores are large, close to the edge of the 

 jaw and partially exposed to view, when the outer papilla is 

 removed. The tentacles of the two or three basal joints are 

 rather large, those beyond decreasing rapidly. The basal 



*It corresponds in position and use with a similar process, found in 

 O. ensifera, O. hirsuta and other species, which in most cases seems to 

 be developed on the angles of the first arm-plate. It is sometimes mov- 

 able, but more frequently solid. (See also group F., p. 43). 



