ECHINODERMATA OF NEW ENGLAND. 15 



Four clusters of tentacles . . Nemopsis. 

 Eight clusters of tentacles . . Lizzia. 



II. Tubes four, branched .... Willia. 



III. Tubes eight, unbranched . . Melicertum. 



Mabel la. 



B. With sense capsules ; sexual organs suspended from 

 radial tubes. 



I. Tubes four, unbranched. 



a. Stomach without peduncle. 



Tentacles numerous, without smaller basal 

 " spurs." 



Obelia. 

 Oceania. 

 Clytia. 



Tentacles numerous, with basal "spurs." 



Eucheilota. 



b. Stomach with peduncle. 



Tima. 

 Eutima. 



II. Tubes numerous. 



Zygodactyla. 



A. I. 



Pennaria. Bell ovate ; tubes four, broad. Tentacles 

 slight projections of the bell-margin at the junction of the 

 radial and circular tubes. 



P. gibbosa. 1 



Hybocodon. Bell globose, asymmetrical. Tubes four, 

 slender. Single tentacle generally with a cluster of bud- 

 ding Medusae at its base. 



H. prolifer. 



Authorities for specific names are given in the index at the end of the paper. 



