^I. roseola.^ This species has an ovate body three to four inches in height and about half as broad. Some individuals are larger. It has [pg158] an eye-spot on the upper rounded side, and at the other end a very large mouth 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 finished 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 swallowing animals as large as themselves. [Illustration: /Idyia roseola/, half natural size: /d/, /e/, /f/, /g/, /h/, rows of locomotive flappers.] ^I. cyanthina.^ This species, found on the northern 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. III WORMS (PLATYHELMINTHES NEMATHELMINTHES ANNULATA) TABLE SHOWING THE CLASSIFICATION OF THE WORMS DESCRIBED IN THIS CHAPTER Phylum =PLATYHELMINTHES= Class =TURBELLARIA= Order ~POLYCLADIDA~ Genera Species ^Planocera^ ^P. nebulosa^ ^Stylochopsis^ ^S. littoralis^ ^Leptoplana^ ^L. folium^ Order ~TRICLADIDA~ ^Planaria^ ^P. grisea^ ^Procerodes^ ^P. frequens^ ^Bdelloura^ ^B. rustica^ ^B. candida^ ^Fovia^ ^F. Warrenii^ Order ~RHABDOCŒLIDA~ Class =TREMATODA= (/External and internal parasites/) Class =CESTODA= (/Internal parasites/) Class =NEMERTINEA= ^Tetrastemma^ ^T. arenicola^ ^Nemertes^ ^N. socialis^ ^N. viridis^ ^Meckelia^ ^M. ingens^ ^M. rosea^ ^Cerebratulus^ ^C. angulatus^ ^Cosmocephala^ ^C. ochracea^ ^Polina^ ^P. glutinosa^ Phylum =NEMATHELMINTHES= Class =NEMATODA= ^Pontonema^ ^P. marinum^ Phylum =ANNULATA= Class =CHÆTOPODA= Subclass =Polychæta= Order ~ERRANTIA~ Families Genera Species