MONOGRAPH OF THE EXISTING CRINOIDS. 



251 



elongated, in marked contrast to the conditions found in the other cirri, but quite 

 similar to the conditions found in the large cirri of species of more primitive genera, 

 and thus indicating the relationships of superficially very different forms. 



W. B. Carpenter, speaking of the development of the centrodorsal in Antedon 

 bifida, says: "At the beginning of the unattached stage the centrodorsal has the 



FIG. 243. 



FIG. 245. 



FIG. 247. 



FIG. 246. 



FIG. '-Ms. 



FIG. 249. 



FIGS. 243-249. 243, VENTRAL VIEW OF THE CENTRODORSAL OF A SPECIMEN OF OoMANTIIUS PARVICIRRA FROM THE PHILIPPINE 



ISLANDS (AFTER P. H. CARPENTER). 244, VENTRAL VIEW OF THE CENTRODORSAL OF A SPECIMEN OF COMANTHUS PARVICIRRA 

 FROM THE PHILIPPINE ISLANDS (AFTER P. H. CARPENTER). 245, VENTRAL VIEW OF TIIE CENTRODORSAL OF A SPECIMEN OF 

 COMANTHUS PARVICIRRA FKOM THE PHILIPPINE ISLANDS (AFTER P. II. CARPENTER). 246, VENTRAL VIEW OF THE CENTRO- 

 DORSAL OF A SPECIMEN OF CoMASTER FRUTICOSUS FROM THE PHILIPPINE ISLANDS. 247, VENTRAL VIEW OF TIIE CENTRODORSAL 



OF A SPECIMEN OF COMANTHUS PARVICIRRA FROM THE PHILIPPINE ISLANDS (AFTER P. II. CARPENTER). 24S, VENTRAL VIEW 

 OF TIIE CENTRODORSAL OF A SPECIMEN OF CoMANTHUS PARVICIRRA FROM TIIE PlULH'PINE IM.ANHS (AFTEK P. H. CARPENTER). 

 249, VENTRAL VIEW OF THE CENTRODORSAL OF A SPECIMEN OF COMANTHUS PARVICIRRA FROM THE PHILIPPINE ISLANDS (AJTER 

 P. H. CARPENTER). 



form of a basin with its lip turned inward; its diameter is about 0.03 inch, and its 

 height about 0.012 inch. Its basal surface is somewhat depressed in the center, 

 and here there is for a tune distinguishable a minute 5-rayed perforation which 

 previously formed the communication between the cavity of the basin and the 



