2 INTRODUCTORY. 



are already known as European forms. These are Filellum immersum, Hale- 

 eimn muricutum, SerMarella polyzonias, Sertularella Gayi, Antemmlaria ramosa, 

 Plumnlaria cutJumna, and probably Tubuluria 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, capilhris Pourtales, has 

 been already examined and named {Thna capillaris) by Mr. de Pourtales 

 in No. 6, Bull. M. C. Z., Vol. I. Mr. de Pourtales has also described Tubuluria 

 crinis, 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 Tubularia 

 indivisa of the European seas ; but as in none of the specimens of apparent 

 Tubularia does anything remain beyond the tubular perisarc, 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 

 I have figiu'ed one form which occurs also on the eastern side of the At- 

 lantic, and has been elsewhere * described by myself as a variety of Sertu- 

 larella Gayi. 



Of the fifty-five new Calyptoblastic species forty-five belong to the Ser- 

 tularinae and ten to the Campanularinae. 



The collection is especially rich in the Plumularida; ; 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 Antemmlaria ramosa and the 

 Plumnlaria caihurina of the European shores. 



• Reports on the Hydroids collected during the Expeditions of H. M. S. Porcupine, Trans. Zobl. 

 Soc, London, February, 1873. 



