164 NUCLEIFER^. 



cells at the base of the tentacles ; the abactinal part of the bell is quite 

 conical (Fig. 259) ; the tentacles of the adult Medusa are usually car- 

 ried rather stiffly (Fig. 260) ; but when the young Medusa is still at- 

 tached, they are frequently expanded several times the diameter of 

 the bell. (Fig. 260.) This Medusa resembles very much the young of 

 Turritopsis nutricula, and could readily be mistaken for it. It would 

 be most natural, therefore, to place this genus in the family of Nuclei- 

 ferce ; but the presence of the peculiar oral tentacles of Lizzia, added 

 to the fact that this is probably only a permanent embryonic stage of 

 Lizzia, induces me to place it among the Bougainvillid^e. 



Allman describes, in the fourth volume of the Ann. & Mag. of N. H. 

 for 1859, page 368, a Medusa as developing from Laomedea tenuis, 

 which resembles so strikingly Lizzia and Dj'smorphosa that I suspect 

 there must be some error in his observation. Does it not rather come 

 from his Dycoryne stricta, which he found at the same time and at the 

 same place, and which would thus bring this Medusa, intermediate in 

 its characters between Lizzia and Dysmorphosa, to its proper place 

 among the Bougainvillidie ? 



Massachusetts Bay, Nahant (A. Agassiz) ; Buzzard's Bay, Naushon 

 (A. Agassiz). 



Family NUOLEIFER^ Less. 



Nuclei/era' Less. Prod. Mon. Med. 1837. 



Nucleiferm Agass. Cont. Nat. Hist. U. S., IV. p. 346. 1862. 



Oceanidce EsCH. (p- p- non Agass.). Syst. der Acal., p. 96. 1829 



Oceanidce Gegexb. ; in Zeitschrift f. Wiss. Zool., p. 219. 1856. 



Oceanidce McCr. Gyran. Charleston Harbor, p. 21. 



Clavidce McCr. Gymn. Charleston Harbor, p. 37. 



ClavidcE Agass. Cont. Nat. Hist. U. S., IV. p. 338. 1862. 



TURRIS Less. 



Turris Less. Prod. Mon. Med. 1837. 



Tunis Agass. Cont. Nat. Hist. U. S., IV. p. 346. 1862. 



Oceania AucT. (^p- p- non Agass.). Medusa. 



Clavula Wright. Hydra. 



Turris vesicaria A. Agass. 



Turris vesicaria A. Agass. ; in Proc. Bost. Soc. Nat. Hist., IX. p. 97. 



This Medusa I formerly supposed to be the Medusa digitalis of 

 Fabricius ; it certainly is not that of Forbes. Since that time I have 

 ascertained that the Medusa digitalis of Fabricius belongs to a dif- 

 ferent family, the Trachynemidae. (See page 57.) It has been found 

 but once at Nahant, in the early part of the spring, and probably 



