PREFACE. xi 



Brauer, of Vienna ; and to Dr. Marshal, of Leiden, as well as to many other conti- 

 nental naturalists, for friendly assistance, either by freely placing at my disposal 

 specimens which I could not elsewhere have obtained or by otherwise aiding me in 

 the object I had in view. 



To specify here the names of our own countrymen from whom I have received 

 assistance woidd be to extend this list of obligations to a much greater length than 

 space will allow. Reference to them in other parts of the work will show that I 

 have not been unmindful of the aid they have afforded me. I cannot, however, 

 avoid expressing in this place my obligations to Professor "Wyville Thomson, Dr. 

 Carpenter, and Mr. J. Gwyn Jeffreys, for having placed in my hands the whole of the 

 hydroids procured in the deep-sea dredgings of the " Porcupine " expedition ; and to 

 Mr. Busk, for allowing me the free use of his collection of hydroids obtained from 

 various parts of the world, and affording facts of much value in the geographical 

 distribution of the order. 



The earlier sheets of the present Monograph had been already printed before the 

 publication of Mr. Hincks's work on the British Hydroids.^ This will account for 

 the absence of all allusion to it in the section devoted to the history of those labours 

 which have contributed to bring our knowledge of the Htdroida to its present stand- 

 point. And yet the literature of hydroid zoology demands a special reference to this 

 valuable work. Eminently critical, with the descriptions accurate and lucid, and with 

 the figures abundant and expressive, it is the most complete systematic work on 

 the Hydroida hitherto published. The large amount of original observations gives it 

 a special value, and its fulness of description and illustration renders it indispensable 

 to every student of the Htdeoida. The delay which has occurred in the publication 

 of the second part of the present Monograph will enable me to cite unreservedly Mr. 

 Hincks's work, without which the synonomy and literature of many of the species 

 here described would be very deficient. 



' ' A History of the British Hydroid Zoophytes.' By Thomas Hincks. London, Van Voorst, 1868. 



