324 BULLETIN OF THE 



together ; in the centre a large rosette of primary plates, a large round 

 one in the centre; a large, rounded pentagonal one in each brachial space; 

 a small narrow one, wedged between these last, in each interbrachial space. 

 Outside this rosette were the radial shields, touching each other ; and, 

 finally, there were two narrow plates, on a radiating line, in each inter- 

 brachial space between the pairs of radial shields, making thirty-one plates 

 on the upper surface. Below there were only three plates in each inter- 

 brachial space, arranged side by side. The mouth-shields were broad, 

 heart-shape ; the side mouth-shields and mouth-papillae nearly as in the 

 adult. Of under arm-plates there were but two (including the one at the 

 corner of the mouth-slit) : of upper arm-plates, only one, on the first joint. 

 There were tentacles on the second and third joints, just as in the adult, 

 and none beyond. The place where upper and lower arm-plates will 

 appear is indicated by a depression, just where the side arm- plates meet ; 

 and in this depression appears a little papilla, or lump, which at last 

 takes on the form of a true plate. Thus, a larger specimen with a disk of 

 3 mm. ami arm of 10 mm. had already nine upper and three lower arm- 

 plates, but none beyond. Oil Sand Key. 270 and 325 fathoms. 



Ophiacantha nieridionalis Lyman, sp. nov. 



Opkiacantlia pentacrinus? Liitken, Addit. ad. Hist. Ophiur. Pt. Ill, 18G9, p. 46. 



Special Marks, — Disk closely beset with minute stumps, each bearing a 

 crown of fine thorns. Six long, very slender arm-spines. Arms five or 

 six times as loDg as the diameter of the disk, rounded and slender. 



Description of a Specimen. — Diameter of disk 4 mm. Length of arm 

 22 mm. Seven mouth-papillae to each angle of the mouth; three on each 

 side, which are short, bluntly tapering, stout, and separated from each 

 other, and one situated immediately below the teeth, which it resembles in 

 form. Teeth three, short, ilat and wide, with a much curved cutting edge. 

 Mouth-shields between a diamond and a heart shape, much broader than 

 long, with the outer side nearly straight, except a projection at the middle 

 point, and a rounded angle within ; length to breadth .4 : .7. Side mouth- 

 shields wide and strong, nearly straight, meeting within, and resting with- 

 out, on the rudimentary first arm-plate, which is conspicuous and strong. 

 Under arm-plates separated by the side plates along the whole arm, wider 

 without than within; bounded without by a clean curve, on the .-ides 

 by a slightly re-entering curve, and within by an obtuse angle; nowhere do 

 they present a sharp corner, their outline being much rounded. Length 

 (1th joint) A mm. Side arm-plates meeting above ami below, their line 

 of juncture being, at the base of the arm, quite as long as the lower arm- 

 plate. Upper arm-plates small, not as wide as the arm, strongly curved 

 without, and with an angle within, so that they form a sort of broad 



