488 MR. B. 'T. BROWNE ON [Mar. 17, 
are of the greatest importance for the identification of the 
species. 
Pop and Lesueur (1809) first described two medusee—Oceania 
flavidula from Nice [ = Dianea flavidula, Lamarck (1817); Phiali- 
dium flavidulum, Haeckel (1877)|, and Oceania phosphorica from 
the English Channel [=Dianwa phosphorica, Lamarck (1817) ; 
Oceana phosphorica, Agassiz (1862); Phialidiwm phosphoricum, 
Haeckel (1877)]. These Haeckel has given as synonyms of 
Phialidium variabile. The original descriptions appear to me to 
be too vague for the identification of the species, as the marginal 
vesicles have been omitted. 
Two other medusz are placed amongst the synonyms by Haeckel 
viz. Hucope variabilis, Claus (1864), and Thawmantias buskiana, 
Gosse (1853). They may belong to the same species, but I perfer 
to keep them apart until their hydroid forms have been recognized, 
as Hucope variabilis belongs to the Mediterranean (Trieste), and 
Thaumantias buskiana to the British Seas. 
Thaumantias buskiana I consider a distinct species, and refer to 
it in this paper under the name of Phialidium buskianum. 
Claus (1864 and 1881) has given an excellent description with 
figures of the growth of the medusa Phialidium (Eucope) variabile. 
It is quite possible that Geryonia planata, Will (1844), from 
Trieste, Thaumantias dubia, Kollioker (1853), from Messina, and 
Phialidium viridicans, Leuckart (1856), from Nice, may be stages 
in developmeet of Phialidium variabile (Claus). 
I have recognized as a distinct species U’hawmantias eymbaloides, 
Van Beneden (1861). It possesses only eight marginal vesicles, 
by which it may be easily distinguished from the other species. 
I refer again to this species under the name of Phialidiwm cymba- 
lowdeum (Van Beneden). 
I have found another species which apparently has been mixed 
up with Phialidiwm eymbaloideum (Van Beneden). I cannot find a 
good description of this medusa by which it may be distinctly 
recognized from the other species. To prevent confusion I propose 
to call this species Phialidium temporarium. It is very much like 
Phialidium ferrugineum, Haeckel (1864), from the Mediterranean. 
_ It may be the same species, but I prefer to keep them apart until 
the hydroid forms of both have been clearly identified. 
According to Hincks (1868) there are four distinct species of 
hydroids, viz. Clytia johnstonii, Alder, Campanulina acuminata, Alder, 
C. repens, Allman, and C. turrita, Hincks, which liberate medusze 
almost identical in form. These, I have but little doubt, will even- 
tually be proved to be connected with meduse belonging to the 
genus Phialidium. At present the rearing of these young meduse 
has not been carried to the stage which is necessary to connect 
them for a certainty with the free-swimming Phialidium. 
PHIALIDIUM BUSKIANUM, Gosse. (Plate XVI. figs. 6 & 6a.) 
During my visit to Plymouth in September 1893 and 1895, I 
collected many specimens of a medusa in various stages of develop- 
