Vol. XXV, pp. 77-84 April 13, 1912 



PROCEEDINGS /?& 



OF THE /CS^ 



BIOLOGICAL SOCIETY OF WASHINGTON /£ 





SIX NEW EAST INDIAN CRINOIDS BELONGING TO 

 THE FAMILY CHARITOMETRIDiE. 



BY AUSTIN H. CLARK. 



In an earlier paper in this volume (pp. 17-28) I described 

 seventeen new crinoids belonging to the families Comasterida? 

 and Zygometridse which had been discovered in the East Indies 

 by the Dutch steamship Siboga. The present paper deals with 

 the new species of Charitometrida' in the same collection. 



Preliminary descriptions of the new forms in the remaining 

 families will he found in the current volumes of the "Notes 

 from the Leyden Museum," the " Zoologischer Anzeiger," and 

 the "Annals and Magazine of Natural History." 



Family CHARITOMP:TRIDjE. 

 Pachylometra crassa sp. nov. 



This form is nearest to P. flexilis, but it possesses stouter cirri which 

 have rather prominent dorsal processes distally, and the arm bases are 

 much smoother, the axillaries and corresponding ossicles being without 

 the characteristic median tubercles and rounded posterior processes. 



The centrodorsal is very large, truncated conical, the sides making a 

 rather small angle with each other, 9 mm. in diameter at the base, 5 mm. 

 across the irregularly convex dorsal pole, and .5 mm. high; the cirrus 

 sockets are arranged in ten columns, usually three to a column, the col- 

 umns being closely crowded interradially, slightly separated radially. 



The cirri are about xxv, 18-22 (usually 20), 32 mm. long, stout and 

 short segmented; the first segment is short, and the following gradually 

 increase in length so that the sixth and following are nearly as long as 

 broad, those in the outer third of the cirri being slightly shorter again; 

 on the seventh a slight broad subterminal dorsal hump makes its appear- 

 ance which slowly increases in height so that the terminal nine possess 

 a prominent broad blunt and well rounded subterminal tubercle which 



13— Peoc. Biol. Soc. Wash., Vol. XXV, 1912. (77) 



