OPHIUROIDEA OF THE BAHAMA EXPEDITION. 41 

 O. gracilis (Ver.) 



O. vicar ins (Lym.) 



O. exigua (Lym.) 



From the old genus Ophiacantha several genera and sub- 

 genera may now be separated with characters that appear to 

 be of as great morphological value as those that character- 

 ize, for instance, Ophiomitra or Ophiochiton. 



The most important of these are here indicated. 



Series I. 

 Ophiacantha (restricted). 



Types, O. sctosa and O. bidentaia. 



Section A. — Typical Ophiacantha. 



To this section a large majority of all the described species 

 belong. 



Section B. — Ophicnlodia, subgenus nov. 



Two, three, or four tooth-papilla? clustered at the tip of 

 the jaws. Otherwise nearlv as in section A. Distal oral pa- 

 pillae not clustered. 



The figures of several species show two paired papil- 

 lae, directed centrally, at the tip of the jaws. They may 

 not always stand on the dental plate and in such cases 

 should be counted as mouth-papillae, but in some cases 

 they have been determined as true tooth-papilla. Prob- 

 ably in this section there may be a central tooth-papillae that 

 has been over-looked in some species, by reason of its posi- 

 tion, higher up on the jaw, or the smaller size. In some cases 

 the central papilla is present on some jaws, but absent on 

 others of the same specimen. It may have been accidentally 

 lost in some examples. Therefore, I consider the presence of 



