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Notes on some Hydromedusae from the Bay of Naples. 



By 

 Chas. W. Hargitt 



of Syracuse University. 



With plates 21 and 22. 



The following- 'notes' on a few Hydromedusae obtained at Naples 

 duriug tbe spring* and summer of 1903 comprise a series of obser- 

 vations upon several species, some of wliich are believed to be new, 

 others more or less rare, and all of more than ordinary biologica! 

 interest. It is believed that the account submitted may have some 

 value both as to the morpholog-ical and faunal facts coneerned as 

 well as a contribution toward a clearer knowled§;e of some hitherto 

 disputed Problems. 



PaeJiycordyle Weisnianni sp. nov. 



Duriug- the month of May I obtained several colonies of an 

 interesting hydroid which in many respects seems closely allied to 

 Pachi/coirlyk napoUtana Weismann, but which will be seen to have 

 some Sharp differences. The colonies were obtained from the Bay 

 of Naples at comparatively small depths and all inhabiting the shell 

 of a living' snail, Fusus rostrata. The hydroids live fairly well in 

 the aquarium, having' been kept under Observation for as much as 

 a week at a time. During- this time several medusae were liberated, 

 thus affording' opportunity for criticai study of the entire life history 

 of the species, exceptiug that of the embryo. As intimated above, 

 the hydroid seems to live 'fairly' well in the aquarium. It was, 

 however, evident that with successive days under this changed en- 

 viroument there was more or less decline in vigor, both of the hy- 

 droid and developing medusae, for the first medusa, which was born 

 during the tirst day in the a(iuarium, exhibited a vigor and activity 



