CRINOIDEA AND ECHINOIDEA 



5 



so long been to the echini, and will make the correct identi- 

 fication of species practicable, if not easy. Identifications made 

 ^vith the following key must be verified by comparison with 

 the original (or with later and fuller) descriptions, or they can 

 have little value. 



Key to the Crinoids included in the present report 



No stalk. 



Basal pinnules (at least the first pair) with a well-marked 

 comb at tip ; mouth usually excentric. 

 Centrodorsal flat and discoidal. 



Cirri with dorsal spines on distal segments. 



II Br. 2 (i. e. the first division series of each ray 

 consists of only two segments) . . . .Neocomatella alata 

 II Br. 4 (3-[-4) (i. e. the first division series consists 

 of four segments, the third and fourth united by 

 syzygy). 



Cirri XV-XXI, with 10-12 segments Nemaster 



insolihis 



Cirri XXX-XL, 12-18 Nemaster iowensis 



Cirri smooth without dorsal spines; only 



10 arms Comactinia echinoptera 



Centrodorsal conical, crowded with about 40 cirri, having 

 14-17 segments of w^hich several proximal ones are very 

 long and slender Comatonia cristata 



Basal pinnules without terminal combs ; mouth central. 



Cirrus segments with dorsal, transverse, serrate ridges, 

 contracting to a single spine on the penultimate segment; 



cirri about XV, 20 Analcidometra aryaata 



Cirrus segments smooth, or with a single spine, dorsally. 

 Cirri very long with 40-60 or more segments, of wliicli 



the distal ones have conspicuous dorsal spines, 



Stylometra spin if era 



Cirri shorter, with 10-20 segments. 



Arms more than 10; cirrus joints stout, even the prox- 

 imal rarely twice as long as broad. 



Cirri XIV-XV, 11-12 Crinomctra graciKt 



