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{From the Proceedings of the Academy of Natural Sciences, Julj, 1855.'! 



^Descriptions of some new Marine Invertehrata. By Wm. Stimpson, Zoologist to the 

 U. S. Surveying Expedition to North Pacific, Japan Seas, etc., under direction of 

 Commander C. Ringgold, U. S. N. 



( Commu nicated by the Smithsonian Instittition.) 



ECHINODERMATA. 



1. Ophiothrix spongicola. Disk covered with short spines, except on the 

 large triangular plates at the bases of the arms ; the sides with scattered, mi- 

 nute spines ; the interbrachial plates below subrhombic in shape. Arms in 

 length seven times the diameter of the disk, broad near their origins but very 

 blender at their extremities ; lateral spines six in each row, the upper ones being 

 largest, subclavate, with rounded extremities, compressed and distantly serrated. 

 The spines near the extremities of the arms are, however, generally pointed. 

 Disk reddish, with black spots symmetrically arranged ; arms red, broadly annu- 

 late with black ; spines pale brownish. Diameter, 4 inches. Found among 

 soft sponges in the circumlittoral zone. 



Hab. Australia, at Port Jackson. 



2. Ophiothrix planulata. Disk and arms much depressed ; the latter in 

 length ten times the width of the former. Disk small, smooth and glossy above ; 

 arm-plates broadly triangular, separated from each other by a row of the small 

 plates with which the rest of the disk is covered. Below, the sides of the disk, 

 between the arms, are soft and covered with short spines ; the interbrachial 

 plates subrhombic, but not very distinct. The mouth-fissures have each two 

 large suckers, but no papillae on their sides. Arms suddenly tapering at the 

 middle ; their superior plates trapezoidal and minutely granulated ; lateral 

 spines five in each row, the middle ones largest, compressed, with blunt extremi- 

 ties, longitudinally striated, and denticulated on their edges. Disk dark green- 

 ish ; arms colored with red and light brown alternately : below white. Taken 

 in fifteen fathoms among dead corals, on " Groper Shoal," in S. Lat., 20° E. Lon. 



leoj. 



3. Ophiolepis perplexus. Arms filiform, in length about seventeen times the 

 diameter of the disk. Dorsal surface of the disk covered with small scales, the 

 arm-plates of each pair being elongated, very narrow, broadest exteriorly, and 

 including a triangular space between them; ventral surface with the inter- 

 brachial plates broader than long ; mouth with a pair of large scale-like papillae 

 at the summit of each projecting angle, and a pair at the base of each fissure. 

 Lateral spines of the arms five in number in each row, short, thick, and pointed. 

 Disk above dark greyish ; arms purplish-brown, darker and lighter alternately ; 

 below reddish. The disk is very soft and is always cast by the animal when 

 caught; the slender arms then twisting together in all directions. Found in the 

 circumlittoral zone in mud. 



Sab, Australia, at Port Jackson. 



