No. 8. — On the Acalephce of the East Coast of New England. By 

 J. Walter Fewkes. 



The ouservations recorded in the following pages are placed under two 

 titles. The first subject, " Medusae from Newport " relates to jelly-fishes 

 taken at Newport, R. I., in the summer of 1881.* Under the second, 

 "Acalephse collected by the U. S. Fish Commission, &c.," will be found 

 descriptions of jelly-fishes taken by them off the New England coast in 

 1880 and ISSl.f 



I. Medusae from Newport. 



CTENOPHORA. 



Development nf the Chymiferous Tubes in M7iemiopsis Leidyi, A. Ag. 



Figs. 1 - 9. 



In the development and nnion of the chymiferous tubes, the larval stages of 

 Mnemiopsis differ radically from those of the closely related genus Bolina, 

 whose embryology is described and figured by Mr. A. Agassiz.J In Bolina, 

 according to the author last mentioned, those ambulacral tubes which are 

 situated nearest the tentacles are the first to unite, "forming thus the first 

 connected loop enclosing in the adult Bolina the complicated winding tubes of 

 the short pair of chymiferous canals of the actinal lobes." 



The first pair of these tubes to unite in the young Mnemiopsis are not the 

 vessels which lie adjacent to the tentacles, but those placed in the body walls 

 between the tentacular rows of combs. It therefore appears, in other words, 

 that the chymiferous tubes which are the last to join in Bolina, are first to unite 

 in the closely allied Mnemiojmx. 



* I am indebted to Mr. Agassiz for facilities to carry on this portion of the work 

 in his private laboratory at Newport, R. I. 



t These medusae have been placed in my hands for study through the kindness 

 of Prof. Verrill. I take this opportunity to express ray indebtedness to him for 

 this and other favors. 



I North American Acalephas, p. 17 ; also Mem. Amer. Acad., Vol. X. No. TIT. 

 Mr. Agassiz has pointed out that the sequence in the \inion of the ambulacral tube.i 

 of Bolina is exceptional. 

 VOL. IX. — NO. 8. 



