160 
reentering sides and a straight outer edge. Adoral shields almost 
meeting within. The ventral plates are very characteristic, elongate, 
a little broader within than without; the proximal one with a con- 
cave inner edge. Farther out they are almost octogonal, with a 
slight concavity in the outer edge. The dorsal plates are transverse 
oval, about twice as broad as long. Two very small teniacle seaks 
(they are not distinet at all the 
pores, but this, evidently, is due 
to the bad State of preservation). 
Five or four simple spines, about 
as long as a joint, the middle 
ones slightly shorter. Whether 
they are naturally appressed, as 
in Fig. 29.3, may well be doubted. 
— The faet that the disk is lost, 
indieates that it is naked as in 
related speeies. The arms are all 
broken, but eonvey the impres- 
sion of being long and siender. 
This speeies agrees so per- 
feetly in its oral strueture and 
in the shape of the ventral plates with Ophionephthys limicola, that 
I do not hesitate in referring it to the same genus. 
Quite reeently H. Ly man Clark has reestablished the genus 
Ophionephthys, whieh was regarded by Matsum o to as a synonym 
only of Åmphiura. Clark eomprises as belonging to Ophionephthys 
the group of speeies of Amphiurids with nearly naked disk, eal- 
eareous seales oeeurring only around the radial shields and rarely 
near the disk margin interradially, with numerous arm-spines, 5-10 
on basal joints and with oral papillae as in Åmphiura. In regard to 
the oral papillæ, however, the type*speeies, O. limicola Ltk. (from 
the West Indies) does not agree with the other speeies, and Clark, 
in faet, is in doubt, whether it was not better to restrict the genus 
so as to inelude the latter speeies alone; sinee otherwise the oral 
papillæ afford the main distinguishing eharaeters of the genera 
2 
Fig. 29. Ophionephthys stewartensis Mrtsn. 
1. Part of niouth and proximal armjoints; 
2. two ventral plates from middle ofarm; 
3. three armjoints from middle of arm, 
dorsal side. i®/i. 
L H. Ly man Clark. Brittle-Stars, new and old. Buli. Mus. Comp. Zool. 
LXII. 1918, p. 278. 
