ECHINODERMATA OF NEW ENGLAND. 



39 



nous in single row. Often obscurely "hooded eyed." Pro- 

 boscis and radial tubes generally present, often absent. 



A. Without proboscis Cunina. 



B. With proboscis. 



I. Body-walls rigid .... Trachyneraa. 



II. Body-walls flexible Liriope. 



Cunina. Body disk-shaped, inflexible, destitute of ra- 

 dial tubes. Tentacles rigid, arise from sides of the body 



j 



CUNINA. 

 SECTION OF THE BELL RIM OF TRACHYNEMA. 



YOUNG TRACHYNEMA. 



not from disk margin. Velum muscular, forming the lower 

 floor of stomach-cavity. 



(7. discoides. 

 B. I. 



Trachynema. Umbrella mitre-shaped with rigid walls, 

 with quick spasmodic movements in propulsion. Onward 

 motion caused in part by vibration of velum. Tentacles 

 numerous with rigid bases. Eight radial tubes, generally 



