574 Cbas. W. Hargitt 



Avith that species. As in the formev species, and as jnst mentioned, 

 no gonophores -vvere present, rendering impossible full determinatiou 

 of the identity snggested. A careful comparison of the hydroid with 

 the descriptious and figures of Hincks leaves little doubt in my own 

 mind. and if later observations of the speeies when the medusae 

 are present shall confirm this view it will extend the ränge of 

 distribution of the speeies to Mediterranean waters, as Calkixs' 

 report of it in 'Hydroids from Puget Sound', has extended its distri- 

 l)Ution to Pacitic waters. 



Gemmaria implexa Alder. 



In 1880 Du Plessis (op. cit.), records the oecurrence of the 

 medusa of this speeies at Naples during the month of March, and 

 makes the verv interesting remark that the si)ecimens taken dififered 

 from typical medusae of the speeies in having 4 complete marginal 

 tentacles instead of 2. »Encore cette meduse diffère-t-elle par 

 (quelques points de celle qui a servi de type aux descriptions qui 

 existent dans les ouvrages anglais. Ainsi cette meduse présente 

 4 tentacules marginaux complets au lieu de deux seuls comme Tiu- 

 dique Allmax«. 



Du Plessis makes no reference to the hydroid and presumably 

 he had only the medusa taken in the 'Auftrieb", which leaves the 

 question of identity an open one, at least in part, and particularly 

 so in that bis medusa had the unusual number of four tentacles. 



On May 13, I obtained a small colony of the hydroid froni 

 which in a short time after having jdaced it in the aquarium a 

 medusa was liberated, and within the following day several others. 

 During the month I obtained about a dozen additional colonies of 

 hydroids and placing them in separate aquaria obtained from most 

 of them free medusae, which lived apparently quite normally for 

 nearly a fortnight, thus afifording ampie time for criticai observatious 

 as to growtli, habits, etc. In PI. 22 Fig. 27 is shown a sketch of 

 the entire colony, and in figs. 28, 29, are shown also sketches of 

 individuai hydranth, and medusa. 



As to habitat ali the colonies obtained by me were found u})on 

 the live shells of small lamellibranch molluscs, ap])arently belonging 

 to the genera Xiicida and Corbida. According to Hinxks and All- 



1 Proc. Boston Soc. N. H. Voi. 28 1899. 



