225 "— 



and full description of the new species, no less than eighteen in num- 

 ber, for another occasion. 



Among the Ctexophor^ we have : 



Two species common to Nahant and Naushon, — Idya roseola, Ag., 

 and PleurohracMa rJiododactyla, and one new species oiBoUna. 



Among DiscoPHOR^: 



Cyanea arctica, Per. and Les., was quite common here, and although 

 I did not observe any species of A urelia, on account of the lateness 

 of the season, I have no doubt that either our common species Aurelia 

 flavidula will be found here, or a representative species ; as we have 

 the genus Aurelia in Charleston and Florida. A new species of Pela- 

 gia was also observed. 



Among the Hydroids, four of the Campanularians are identical 

 with the species found at Nahant, and one of them, which McReady 

 has named Ohelia commissuralis, is found at Nahant, Naushon, and 

 Charleston. The three others are Clithia bicopJiora, Laomeda diapfiana, 

 and Campanularia amphora.^ The genera' Epenthesis, Eutima, Ew- 

 cheilota, Turritopsis, Dipiirena, of McReady, were all represented 

 each by one species, as well as Sarsia, StomobracMum, Willsia, A trac- 

 tylis, Pennaria, Slabheria, Nemopsis, Bougainvillia, and a species of 

 Thaumantias, closely allied to T. mediterranea of Gegenbauer ; two 

 species of Eudendrium ; one new genus closely allied to Eucheilota. 



This would make in all twenty-seven species of Acalephs, of which 

 six species are common to Nahant and Naushon, two species or per- 

 haps three to Charleston and Naushon, one which is common to 

 Charleston, Boston, and Naushon, leaving seventeen species found 

 thus far only in that Fauna. 



The twenty-seven species observed can be aiTanged as follows : — 



One species common to Charleston, Naushon, and Nahant. 



Six species common to Nahant and Naushon. 



Two species common to Naushon and Charleston. 



Five species which are representatives of genera found at Nahant, 

 Naushon, and Charleston. 



Two species which are representatives of genera occurring at 

 Nahant and Naushon. 



Sev6n species which are representatives of genera common to 

 Charleston harbor and Naushon. 



Three species belonging to genera which had not yet been ob- 

 served on our coast (Atractylis, Slabberia, and a true Tliaumantias). 



One species belonging to an entirely new genus. 



Of these, twenty-four were free Medusa and only three fixed 

 Hydroids. 



Prof. Agassiz remarked that these observations coincided 

 with the zones of distribution of our Crustacea as stated by 



PROCEEDINGS B. S. X. H.— VOL. VIIT. 15 NOVEMBER, 1861. 



