OPHIUROIDEA OF THE BAHAMA EXPEDITION. 35 



This family, as here understood, includes the following de- 

 scribed genera: Ophiacantha, Ophiomitra, Ophiotrema, 

 Ophiocamax, Ophiolebes, Ophiothamnus, Ophiocopa, Ophio- 

 chiton, Ophiotoma, and probably Ophioblcnna. To these I 

 have now added several others, separated from Ophiacantha, 

 Ophiomitra, and Ophiopsila. 



The first six of those named above have the disk covered 

 with scales bearing spinules or thorny processes, or some- 

 times granules. Ophiochiton and Ophiocopa have naked or 

 nearly naked scales. Ophioblcnna and Ophiotoma are cov- 

 ered with naked skin. The radial shields may be large or 

 small, naked or concealed. 



The family is characterized by the prominent and highly 

 developed side arm-plates, usually meeting above and below, 

 and by the numerous, usually long, and more or less rough 

 spines, which stand out at nearly right angles to the arm. 

 The spines may be solid or hollow, glassy or opaque, terete or 

 flat. 



The mouth-papillae are usually rather numerous, and form a 

 continuous row along the side of the jaw, but the outer ones 

 may be of larger size or different in form from the others, or 

 clustered, and in such cases they are really the distal oral 

 tentacle-scales. There may be only a single apical tooth- 

 papilla, or there may be two or three, and sometimes there is 

 a large cluster. In some cases the outer oral tentacle-pore is 

 exposed to view on the outer margin of the jaw and then it 

 has one, or sometimes several, special oral scales or papillae 

 by its outer side, or partly surrounding it. Some of its scales 

 may be attached to the adoral plate, or even to the first un- 

 der arm-plate. This plate is usually concave or somewhat 

 bilobed, and has two inner, lateral, scale-like processes, which 

 are sometimes movable and papilliform. There is generallv 

 a single acute tooth-papilla at the tip of the jaw, but there 

 may be two or three, and in some cases {Ophiocamax, Ophio- 

 mitra, Ophiotrema}, there mav be a cluster of several spini- 

 form tooth-papillae. These were counted as mouth-papillae 



