viii THE VOYAGE OF H.M.S. CHALLENGER. 



Part XX. — At the request of the \site Sh- C. Wy ville Thomson, Dr. Alhnan 

 kindly undertook to prepare a Report on the Hydroida collected hy the 

 Expedition. 



It is with much pleasure that we publish the first instalment of Dr. 

 Allman's Report, which embraces the Family Pluraularida?. This is an 

 important addition to his previous A^aluable work upon this group of animals. 



Part XXI. — In jjublishing a paper by Dr. W. B. Carpenter, it may be per- 

 mitted to recall the prominent part he took in all the preliminary Exj^editions 

 and negotiations which led ultimately to the despatch of the Challenger on her 

 circumnavigating cruise. On the return of the Expedition Dr. Carpenter 

 undertook to prepare a Report on the specimens of OrhitoUtes — a genus to 

 which, as is well knoAvn, he has given special attention — and tlie present 

 Monograph embodies the result of his investigations. 



The whole work which it is proposed to take up in connection with tlie 

 Olilicial Reports on the Scientific Results of the Challenger Expedition is now 

 in active progress, and it is estimated that all the Reports will be published 

 by midsummer of the year 1887. The following List shows the present state 

 of the Reports. The type specimens described in the Published Memoirs have 

 l)een deposited in the British Museum. 



Joux Murray. 



Challenger Office, 

 Edinburgh, 20rt Julij 1883. 



