A. E. Verrill — North American Ophiuroidea. 367 



In having a regular row of teeth and simple normal under arm- 

 plates this group resembles ordinary Ophiurm and differs widely 

 from the Gorgonocephalidoe. 



Subfamily, Euryalinae, nov. 



Arms wide at base, many times dichotomous, with short inter- 

 nodes, bearing two dorsal rows of spines. Disk large, with ten 

 granulated radial ridges. Radial shields long, narrow, composed of 

 only one piece, covered, like the rest of the disk, with cuticle. Inter- 

 brachial areas, below, covered with strong united plates. 



The type, Euryale aspera Lam., is from the East Indies and China 

 Sea. 



Subfamily, Trichastrinse Ljung., 1872. 



Disk relatively small, but thick, with ten stout radial ribs. Arms 

 angular, stout and high at base, divided only distally into a small 

 number of forks. Tentacle-scales short and stout, about three in a 

 row. 



Oral shield well developed. 



The type, Trichaster palmiferus (Lam.), is from the East Indies. 



The arras have two dorsal rows of short, stout, obtuse, conical 

 spines ; they generally occur on alternate ridges. 



The teeth are very large and thick, with truncate ends. Usually 

 there is a single, large, conical tooth-papilla at the apex of the jaw. 

 Oral papilla? small, pampiniform, in two or more rows. The disk and 

 arms, above and below, are rather coarsely granulated. 



Family, GORGONOCEPHALID-ffiJ Verrill. 



GorgonocejJhalince {ijars) Ljung., 1867. Bell, Catal. Brit. Ecbinod., p. 27, 



1892. 

 Gorgonocephalidoe Verrill (restr.), Ophiur. Bahama Exped., Bull. Univ. of 



Iowa, V, p. 83, 1899. 



Arms divided dichotoraously into numerous branches. Disk 

 swollen, with ten prominent radial ribs, covered with cuticle, which 

 may bear granules or scattered spinules, or it may be more or less 

 naked. Radial shields, each composed of several united plates. 



The entire surface of the arms and disk above and below is 

 covered with cuticle which is usually granulated, so that the plates 

 are hidden. 



Under arm-plates mostly rudimentary, consisting of two or more 

 small pieces, sometimes absent. Side arm-plates are united below 



