Yerrill, Notes on JRadiata. 265 



acute point outwardly and a slight angle inwardly. The side mouth- 

 shields are elongated transversely and do not meet within. Mouth- 

 papilla? one on each side of the mouth-slits, short and stout. Lower 

 arm-plates rounded octagonal ; upper plates broad-oval, a little over- 

 lapping, most convex outwardly. Arm-spines five, the middle one 

 longest. 



Callao, Peru, — F. H. Bradley. The specimens of Dr. Ltitken and 

 3Ir. Lyman came, also, from the same place. 



Ophiactis Virescens Latken, op. dt. ; Lyman, op. cit., p. 113. 



This si)ecies may readily be recognized by the upper arm-plates, 

 which are twice as broad as long and have a distinct, projecting lobe 

 in the middle of the outer edge. The arms are somewhat nan-owed 

 at the base and very slender at the ends. Under arm-plates as long 

 as broad, octagonal. Mouth-shields roundish rhomboidal, with an 

 angle inward. Two small mouth-papillie on each side of mouth-slits. 

 Five or six arm-spines, short and stout, rough, upper two longest. The 

 disk-scales bear a few scattered spines, which are sometimes wanting. 



Color yellowish green, with narrow dark green bands on the arms, 

 beneath greenish gray. The radial shields are dark green and often 

 have a light spot on the outer ends. 



Our specimens all have six arms, except the very young, which 

 lack three, on one side. The largest has arms • 75 of an inch long, with 

 a disk 'IS in diameter. Another has arms '4 inch, with the disk -12. 



Panama, clinging to Gorgonife and sponges. Occasionally adhering 

 among the arm-spines of Ophiothrix sjnculata^ — F. H. Bradley. It 

 occurs at Puntarenas and Realejo, — Dr. Ltitken ; and Cape St. Lucas, — 

 J. Xantus, (Smiths. Listitution). 



In one instance I found, in a small cavity of a branching sj^onge 

 from the Pearl Islands, upw^ards of fifty specimens of this species, of 

 various sizes, but mostly young. Thirty-seven were quite small, and 

 light colored, and although many had six equal arms, others, of sim- 

 ilar size, had three upon one side. Aery small, appearing as if just 

 starting to grow, or entirely wanting. From this mode of occurrence 

 it is probable that this species, like some Amphiuroe, is ovo-viviparous. 



In this lot were two specimens diflering considerably from all the 

 others. These are among the largest, and have the arms narrowed at 

 base; seven arm-spines, upper ones longest; large radial shields, 

 covering a large part of the disk ; broad upper arm-plates, con- 

 vex outwardly, and destitute of a distinct lobe, or with only a slight 

 central prominence, except near the ends of the arms, where a small 

 distinct lobe is visible. In most other respects they agree well with 



