Vol. 30, pp. 151-158 July 27, 1917 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



THREE NEW STARFISH AND ONE NEW BRITTLE-STAR 



FROM CHILE. 



BY AUSTIN H. CLARK.* 



While working off the coast of Chile from the ninth to the 

 twelfth of February, 1888, the "Albatross" brought to light 

 three new starfish and a new ophiuran, the descriptions of 

 which follow. 



Family ASTROPECTINID^E Gray. 

 Plutonaster sirius, new species. 



Five arms; R=33 mm. ; r=ll mm. ; R: r=3:l ; superomarginals 24 to 

 26. 



The coeca extend to the fourth supermarginal. 



The gonads are not developed. 



The ampullae are conical with the base (the actinal end) hemispherical ; 

 the pedicel is attached near the base. They may thus be described as 

 single, with a slight actinal swelling. 



The abactinal skeleton is composed of irregular rounded plates. 



The abactinal surface is covered with closely set, though not crowded, 

 paxillse; these are very uniform in size, but are smaller on the center of 

 the disk and on the outer part of the arms than elsewhere. At the sides 

 of the arms and around the interbrachial arc they are arranged in trans- 

 verse rows; in the center of the disk and in a band down the center of 

 each arm their arrangement is irregular. The paxillse have a low tabu- 

 late base, rarely so high as broad at the convex summit, bearing in the 

 larger from twelve to sixteen spinelets which are longer than the height 

 of the tabulate base, of which the peripheral make a slight angle with, 

 the vertical axis. 



The surface of the large compound madreporite is concealed by five or 

 six much enlarged paxillfe, most of which are situated around its 

 border. 



The papulfe, which are small and regularly arranged about the bases 



• Published with the permission of the Secretary of the Smithsonian Institution. 

 37— Proc. Biol. Soc. Wash.. Vol. 30, 1917. (151) 



