2, INTRODUCTORY. 
are already known as European forms. These are Filellum immersum, Hale- 
cium muricatum, Sertularella polyzonias, Sertularella Gayi, Antennularia ramosa, 
Plumularia catharina, and probably Tubularia indivisa, whose identification is, 
in consequence of the absence of all the soft parts, less certain than in the 
others. 
One of the specimens here described, Halecium capillaris Pourtalés, has 
been already examined and named (Z'hoa capillaris) by Mr. de Pourtalés 
in No. 6, Bull. M. C. Z., Vol. I. Mr. de Pourtalés has also described Tubularia 
crims, but this has not been received by me in a condition sufficiently 
perfect to admit of further examination. 
The Gymnoblastic genera sufficiently well preserved for satisfactory de- 
termination consist of nine species, all new and referable to two genera, 
Eudendrium and Bimeria. Species of Tubularia would also seem to exist 
in the collection, and one of these, as just said, is probably the Tudbularia 
mdivisa of the European seas; but as in none of the specimens of apparent 
Tubularia does anything remain beyond the tubular perisare, the characters 
needed for a reliable determination are entirely wanting. 
Several of the specimens referred to Eudendrium have, on the contrary, 
their soft parts well preserved, and leave no doubt of the correctness of 
this determination; while others may, with a provisional reservation, be 
referred without much hesitation to the same genus. In the little hydroid 
referred to Bimeria the soft parts are well preserved both in the tropho- 
some and the gonosome. 
Of species referable to Calyptoblastic genera fifty-six are here described 
and figured. Of these, fifty-five are now recorded for the first time, while 
Ihave figured one form which occurs also on the eastern side of the At- 
Jantic, and has been elsewhere * described by myself as a variety of Sertu- 
lurella Gayi. 
Of the fifty-five new Calyptoblastic species forty-five belong to the Ser- 
tularine and ten to the Campanularine. 
The collection is especially rich in the Plumularidz ; no less than twenty- 
eight out of the seventy-one determinable species belong to this beautiful 
family. Of these, twenty-six species are now described for the first time, 
the remaining two, so far as it is possible to determine specimens in which 
no gonosome is present, are identical with the Axtennularia ramosa and the 
Plumularia catharina of the European shores. 
* Reports on the Hydroids collected during the Expeditions of H. M. S. Porcupine, Trans. Zool. 
Soe., London, February, 1873. 
