78 PROCEEDINGS OP THE ACADEMY OF [Feb., 



and undata of Lyman, 0. prisca, laudata, and distincta of Koehler, 

 and Ophiura megapoma, hadra, and penichra of H. L. Clark; also the 

 following species with the ventral interbrachial areas covered with 

 many scales, and having axe-shaped ventral arm plates, Ophio- 

 glypha radiata and ornata of Lyman, and 0. abcisa and ohtecta of 

 Llitken and Mortensen. 



The group with very large oral shields or with very conspicuous 

 ventral interbrachial plates approaches Ophiopyrgus on the one 

 hand and Aspidophiura on the other; the group with ventral inter- 

 brachial areas covered with many scales and with quadrangular 

 ventral arm plates approaches Gymnophiura on the one hand and 

 Stegophiura (vide infra) on the other; and the group with ventral 

 interbrachial areas covered with many scales, and with axe-shaped 

 ventral arm plates, approaches true Ophiura, restr. (vide infra). 



GYMNOPHIURA Liitken and Mortensen, 1899 (restr.). 



Disk high, covered by a naked skin. Radial shields long, narrow, 

 bar-like, widely separated from each other, covered by skin. Arm 

 combs and genital papillae present. Oral shields comparatively 

 small, pentagonal, with notched lateral sides. Second oral tentacle 

 pores opened partially outside the oral slits, large, with numerous 

 scales. Arms moderately long, very gradually tapered outwards, 

 with blunt extremity. Dorsal and ventral arm plates well developed, 

 successive plates widely in contact with each other. Lateral arni 

 plates high, with numerous minute, peg-like arm spines. Tentacle 

 pores large, with numerous scales. 



This genus, as restricted, contains but a single species, G. tnollis 

 Liitken and Mortensen. Another species, viz., G. coerulescens, is, 

 in my opinion, referable to genuine Ophiura, and is probably con- 

 specific with, or at least closely allied to, Ophiura flagellata (Lyman). 



Gymnophiura is very near Amphiophiura, especially the group 

 with ventral interbrachial areas covered with many scales, and with 

 quadrangular ventral arm plates, but differs from it in the naked 

 disk and in the radial shields, which are narrow, bar-like, skin-covered 

 and widely separated from each other. 



STEGOPHIURA gen. nov. 



Disk high, covered with plates and scales, among which the 

 primaries are prominent. Radial shields stout, joined distally. 

 Arm combs and genital papillae present. Oral shields oval or pyri- 

 form. Second oral tentacle pores open more or less, or entirely, 



