MONOGRAPH OF THE EXISTING CRINOIDS. 



229 



appears to be merely an exaggerated concavity of the dorsal pole, exactly compar- 

 able to the conditions found in many recent species — for instance, in ComaniJius 

 Icnnetti and m C. pinguis (figs. 171-174, p. 231). There is no reason whatever for 

 supposing that the centrodorsal in any fossil species was open at the dorsal pole any 



F:g. 165. 



Fig. 166. 



Fig. 168. 



Fig. 167. 



Fig. 169. 



Fig. 170. 



Figs. I6j-1"0.— 165, The centrodorsal and radials of a specimen of Comanthina schlegelii from the Philippine Islands 

 (AFTER p. H. Carpenter). 166, The ce.ntrodorsal and eadials of a specimen of Comanthina scin,EGELn from the 

 Philippine Islands (after P. H. Carpenter). 167, The centrodorsal, radi.u.s, and IBe series of a specimen of 

 Comantheria altern.\-ns from the Philippine Islands with two atrophied cmni remaining. 1&% The centeodors.u. 

 .vnd raduls of a specimen of Comanthina schlegelu from the PuiLipprNE Islands (aj-ter P. H. Carpenter). 169, 

 The centrodorsal and radials of a specimen of Com.^nthina schlegelu from the Philippine Islands (after P. H. 

 Carpenter). 170, The centrodorsal and radlals of a specimen of Comanthina schlkoelh from the Philippine 

 Islands (after P. H. Carpenter). 



more than it is in any recent species, and there is no evidence wliich undeniably 

 supports such a view. 



The comatulid centrodoi-sal varies in shape from a small stellate or pentagonal 

 plate, smooth at the edges and sunk beneath the dorsal surface of the radial penta- 

 gon (figs. 82, p. 135, 153-159, p. 221, 162, p. 223, 164, p. 227, and 16S-170, p. 229), 

 or a tliin (hsk more or less concave doi-sally with a single, often partially deficient. 



