A. E. Verrill — North American Ophiuroidea. 315 



A. canescens (Lym.) V., Pacific, 600 fath.; A. glauca (Lym.) V., 

 Pacific, 345-420 fath.; A. cernua (Lyra.) V., Pacific, 2300 fath.; A. 

 patula (Lym.) V., Antarctic, 1976 fath.; A. dalea (Lyra.) V., S. 

 Atlantic, 2650 fath.; A. Icevis (Lyra.) V., Philippines. 



Amphioplus Agassizii Ver., sp. nov. 



Amphiura, sp., Lymau, Bull. Mus. Comp. Zool., vol. x, p. 253, pi. v, figs. 

 64-66, 1883. 



Disk covered with minute scales, of neai'ly uniform size, not form- 

 ing a central rosette. Radial shields narrow, separated by several 

 rows of small scales. Oral shield obovate or pear-shape, evenly 

 rounded distally, longer than broad, sides a little incurved. Adoral 

 plate long, narrow, three-lobed, not meeting proximally. Oral 

 papillae six; of these the four inner ones are sraall, conical; the two 

 outer are larger and broader and attached to the adoral plate. 



Arm-spines three, slender, tapered. Tentacle-scales two, rounded. 

 Under arm-plates are wider than long, broadly in contact and trun- 

 cate at both ends. Upper arm-plates are broadly triangular, short, 

 barely in contact. 



This species, which was well figured by Mr. Lyman, but not 

 named, is allied to A. nereis, but the latter has only five oral 

 papillae, of which four are stouter and blunter, while the outer one 

 is minute ; its oral shield is rounder; its under arm-plates are barely 

 in contact, and have an inner angle ; its arm-spines are larger and 

 its disk-scales are also rather larger. 



West Indies, 116 fath., Blake Exp, 



Ophiocnida Lyman. 



Subdivisions. 



That this genus, as recognized by Mr. Lyman in his later works, 

 is a heterogeneous group has been noticed by more than one writer. 

 Mr. Lyman, himself, intimated as ranch in the Voyage of the Chal- 

 lenger. According to his view no difference exists between this 

 genus and Amjyhitfra except that Op)hiocnida has spines or grains 

 on the disk. But some of the species have only a few granules, 

 while at least one species that he referred to Amphiura (A. LidJceni) 

 also has some small spinules on the disk, so that this distinction 

 seems to be of little real value, taken by itself.* But as Mr, Lyman 



* The same holds good in other cases. Thus Ophiacantha in some upecies has 

 only granules, and O. loBvipelUs often has naked scales. (See p. 843.) In Ophio- 

 thrix similar variations are found. 



