158 



MARINE INVERTEBRATES 



an eye-spot on the upper rounded side, and at the other end a very 

 large inouth opening into a digestive cavity, which occupies the greater 

 part of the body. A delicate fringe surrounds the 

 area about the eye-spot, and eight rows of cilia run 

 from there to the oral end. It has no tentacles. Idyia 

 is pink and especially highly colored at the spawning- 

 time. Like other jellyfishes, their part in life is fin- 

 ished when they have discharged their spawn, and the 

 first September storms break them to pieces. In July 

 and August they are plentiful on the New England 

 coast. They appear at the surface of the water in 

 the hottest part of the day, but disappear entirely 

 when the water is in the least rough or the weather is 

 cold or the sun overcast. Their movements are slow 

 and graceful, the long axis being carried in a nearly 

 horizontal position. They are exceedingly voracious, 

 feeding chiefly on other Ctenophora, and often swal- 

 lowing animals as large as themselves. 



I. cyanthina. This species, found on the north- 

 ern Pacific coast, broadens near the center, making it somewhat vase- 

 shaped. Idyopsis Clarkii, a similar genus, found in Florida, is globular. 

 All these species are very beautiful, the rapid movement of the cilia giving 

 them a brilliant iridescence. 



Idyia roseola, half nat- 

 ural size : d, e, /, g, h, rows 

 of locomotive flappers. 



