NO. 2257. A NEW OPHIURAN FROM THE CARIBBEAN SEA. 639 



outer half of the disk scattering straight lines, running parallel to 

 the periphery, of from 3 to 12 (usually from 6 to 12) closely ap- 

 pressed tubercles, some of which usually carry conical teeth similar 

 to those borne by the transverse lines on the ribs. These lines become 

 increasingly common outwardly. 



Orally the interradial portions of the body are covered with very 

 fine grains, among which are numerous larger and lighter-colored 

 grains grouped in such a way as to form a close-meshed marbling or 

 reticulation. 



The entire under surface of the arms is covered with a uniform 

 investment of fine grains, which become coarser proximally and 

 largest beneath the disk, where, on account of their increased con- 

 vexity, they are especially prominent in the interradial angles. 



The five madreporic plates, which are short and broad and more 

 or less reniform or crescentic, lie in the adoral angles of the inter- 

 radial areas. 



The teeth, tooth papillae, and mouth papillae are all very long, and 

 do not differ greatly in length. The teeth distally become broadened 

 and flattened, with chisel-like ends. 



The genital slits are short, 3 mm. to 5 mm. in length, not more 

 than one- fourth of the distance from the arm base to the adoral 

 interradial angles in length. 



The arms divide eight or nine times, the first fork being beneath 

 the disk, and the second on its border. In the second division the 

 outer branch is shorter, but stouter, than the inner ; it consists of 6 or 

 7 segments, while the inner consists of about 10. In the third division 

 the inner branches are longer and somewhat stouter than the outer, 

 though both consist of 8, more rarely of 9, segments. The following 

 divisions to the arm tips all consist of 8 or 9, more rarely of 10, 11, 

 or 12, segments, and in each case the inner branch (in reference to 

 the preceding division) is slightly stouter than the other. 



The tentacle papillae appear immediately, or very shortly, after the 

 second forking. At first they are one, or (usually) two, in number, 

 and small and inconspicuous, but after the third fork they become 

 longer and more prominent and the number increases to three, which 

 seems to be the ultimate number. These tentacle papillae are almost 

 identical in size and in appearance with the jointed conical teeth 

 which extend in transverse bands across each arm segment, and 

 merely form the ventral terminal portions of these bands. On a 

 superficial examination it is impossible to differentiate them. 



The dorsal and lateral surface of the arms is covered with a pave- 

 ment of thickly set granules, which pass over uninterruptedly into 

 the similar granules of the ventral surface. 



