268 YerriU^ Notes on Radiata. 



Ophiothrix (Ophiothela) mirabilis Verriii, sp. nor. 



A small species witli six arms, granulated above ; disk mostly cov- 

 ered by the larg-e radial shields, and in the longer specimens with cen- 

 tral and interradial groups of simple, short, conical spines ; arm-spines 

 short, directed downward, armed with hooks. Teeth-papillae about 

 ten, rounded, arranged in an oval group. Mouth-shields and side 

 mouth-shields closely united to the surrounding parts, so as to form a 

 continuous ring around the mouth, covered with a skin which conceals 

 their outlines, the side mouth-shields about as large as the mouth- 

 shields. Under arm-plates about as long as broad, widest outwardly, 

 the outer edge convex, the sides converging to the rounded inner 

 angle, separated by the side arm-plates, and covered, like the mouth- 

 shields, with a naked skin, Avhich obscures their outlines even in dry 

 specimens. Side ann-plates well developed, bearing upon the very 

 prominent sides about five tapering spines, of which the uppermost is 

 quite small, the next and longest about equal to the width of arm, the 

 others decreasing in size to the lowest, which is very small. When 

 six spines occur the third is the longest. Toward the base of the arms 

 the spines are minutely thorny near the ends, the thorns being chiefly 

 on the lower side of the spines, irregular, and often curved ; toward 

 the middle of the arms and beyond, the thorns become more nume- 

 rous, larger and curved into well-marked hooks. Disk nearly covered 

 above by the twelve prominent, elongated radial shields, which reach 

 nearly to the center and are narrow and blunt at the outer ends. They 

 are in contact, except along the inner portion, where they are slightly 

 separated. Their surface is minutely pitted and more or less covered 

 by scattered, unequal, rounded granules. Between the radial shields 

 and at the center, the surface is covered by a distinct skin, without 

 visible scales. In the interbrachial spaces at the margin of the disk 

 there is a cluster of about six sharp, conical spines, without thorns. 

 A cluster of similar spines sometimes occupies the center. In young 

 specimens the spines are absent. The upper arm-plates are concealed 

 by the skin, which is covered by numerous, rough, unequal, rounded 

 grains, the intervals between the plates being indicated by narrow, 

 transverse, naked spaces. 



Color, in alcohol, quite variable, usually dark. One specimen has 

 the disk grayish brown, the outer ends of radial shields bright yellow ; 

 the arms with narrow bands of grayish white, bright yellow, and 

 black ; beneath .yellowish brown, the under arm-plates minutely 

 speckled with dark brown. Another has the disk, above, deep red- 

 dish brown, with a lighter center ; the outer ends of the radial shields 

 yellowish white ; the upper side of arms transversely banded with 

 dark brown and yellowish white. 



