190 Rev. A. M. Norman on the Circumpolar 
Diphasia mirabilis, Verrill, described originally from Le 
Have and St. George’s Banks, on the New-England coast, and 
subsequently figured by Clark from the Alaskan Sea. 
The genus Polysertas will also be synonymous with Sela- 
ginopsis, lately described by Prof. Allman, with a type (S. 
fusca) found in Japan *. The White-Sea species will there- 
fore be.Selaginopsis mirabilis (Verrill). 
Until quite recently the Hydrozoa have been almost en- 
tirely neglected in all seas except our own, though we must 
not forget the important investigations of L. and A. Agassiz. 
We thus know very little of the geographical distribution of the 
species. Selaginopsis mirabilis is the first arctic Hydrozoon 
which has been described from the east and west coasts of North 
America and subsequently found in the north of Europe. 
It is no wonder, therefore, that Mr. Mereschkowsky, having exa- 
mined European literature without finding his species, should 
have supposed that it was new. The reseazches of Vervill on the 
New-England coast are materially extending our knowledge of 
the distribution of many classes, including the Hydrozoa, on 
the western side of the Atlantic; and Mr. 8. F. Clark’s ad- 
mirable report on the Hydrozoa of Alaska has special interest. 
In it he figures, and describes when necessary, forty-two 
species as inhabiting the district. No less than sixteen of 
these are Arctic species which reach the British coast, and 
the circumpolar distribution of which has now been estab- 
lished. They are :— 



Obelia longissima (Pallas). Calycella syringa (Linn.). 
Clytia Johnstoni (Alder). Coppinia arcta (Dalyell). 
Campanularia integra, Macgil. Halecium muricatum, Johnst. 
Gonothyrea hyalina, Hincks. Sertularia filicula, Z. & S. 
Lafoéa pocillum ?, Hincks. Sertularella tricuspidata, Alder. 
gracillima (Aldcr). rugosa (Linn.). 
—— dumosa (Fleming). ——- polyzonias (Linn.). 
fruticosa, Sars. Tubularia indivisa, Linn. 
Add to these Selaginopsis mirabilis and we have two fifths 
of the Alaskan species with a known circumpolar distri- 
bution. 
Selaginopsis and Pericladium are apparently Arctic genera 
which have reached Japan by way of Kamtschatka and the 
Kurile Islands—the course of distribution which has caused, I 
believe, the striking resemblance in many features between 
the British and Japanese marine faunas; and I venture to pre- 
dict that many genera which are common to Japan and Kuro- 
* Linn. Soc. Journ. vol. xii. (1876) p. 272. Another of Clark’s 
Alaskan species, Thuiaria cylindrica, belongs to Aliman’s genus Pert- 
cladium, described in the paper just quoted, p. 273. 
