366 A. E. Verrill — North American Ophiuroidea. 



Family, OPHIOBRACHIONTIDiE Verrill, nov. 



Disk entirely covered with acute spinules and cuticle, without 

 radial shields or ribs. Arras long, slender, serpentine, so covered 

 with cuticle that the plates are hidden. Under arm-plates are pres- 

 ent. Side arm-plates not prominent, bearing rows of small double 

 hooks on all the joints, but no spines. Uijper arm-plates rudimen- 

 tary or lacking. Tooth-papillse spiniform, in an apical cluster ; a 

 few similar mouth-papilla3. 



The only species, Ophiohrachion unchiatus Lym., is from off 

 Cuba, in 250 fathoms. 



Order II, EURYALiE Miill. and Trosch., 1842. 



EuryalidcB Gray, Synop. Brit. Miis., p. 63, 1840. 



Astrophytonidce Norman, Ann. and Mag. Nat. Hist., xv, p. 104, 1865. 



Phytastra Hseckel, Gen. Morpli. , ii, p. 67, 1866. 



Astrophytida' Lyman, Ljnngman, and others. 



Euryalce Miill. and Troschel, Syst. Aster., p. 85, 1842. Ljung., Oph. Yiv., p. 



334, 1867. Cams, Fauna Medit., p. 97, 1884. Verrill, Ophiur. Bahama 



Exped., p. 73, 1899. 

 Cladophiurm Bell, Proc. Zool. Soc. London, Tp. 180, 1892; Catal. Brit. Echinod., 



p. 26, 1892. 

 Euryalida of several authors. 



Family, EURYALIDA {2Jars) Gray, 1840, restricted. 

 AstrophytidcB {pm-s) Lyman, and many other authors. 



Arms more or less dichotomous. Disk covered with cuticle and 

 granules, and having ten strong radial ridges. 



Teeth strong and large, in a single vertical row, as in Ophiurae. 

 Tooth-papillfe, few or none. Oral papillae minute, papilliform, or 

 lacking. Adoral shields and jaw-plates large, well formed. Oral 

 shields rudimentary. 



Under arm-plates simple ; they extend the whole length of the 

 arm. Side arm-plates small, appressed proximally, but prominent or 

 erect distally, where they bear double claw-like hooks and thorny 

 spinules ; toward the base of the arms they bear few, small, rough, 

 simple spines or tentacle-scales. Two rows of small plates, extend- 

 ing up from the side-plates, form transverse ridges, around the arms. 

 Large spines, along the upper side of the arm, are borne by some .of 

 these plates. Dorsal arm-plates are represented only bj' small 

 detached pieces. 



