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



with a group of Deep-Sea Keratosa. These are interesting from the 

 symbiosis with Hydroids, from the mass of the pseudo-skeleton, consisting 

 of the materials of deep-sea deposits, from the primitive forms described under 

 the name Ammoconidoe, and the difficulties which were experienced by many 

 naturalists in determining the true nature of these remarkable organisms. 



The Eeport extends to 92 pages, accompanied by 8 chromo-lithographic 

 plates. 



This volume concludes the Zoological Series of Eeports on the Scientific 

 Eesults of the Expedition, with the possible exception of a few supplementary 

 notes to some of the memoirs and Professor Huxley's Eeport on the genus 

 Spirula, which may appear as an appendix to the concluding Summary 

 Volume. 



The first volume of these Zoological Eeports was issued in 1880, and the 

 others have appeared at short intervals up to the present time. During the 

 same period there have been issued from the press two Botanical Volumes, 

 one volume of Physical and Chemical Eesearches, and three volumes of the 

 Narrative of the Cruise with appendices. A second Physical and Chemical 

 Volume will be published within the next two months ; the volume on Deep- 

 Sea Deposits will follow next year, and the whole work will be completed in 

 a Summary Volume. 



As the Biological Series of Special Eeports may now be said to have been 

 completed, there is appended a list of these arranged, first, according to 

 the subject matter, and, second, according to the contents of each volume. 

 Of Zoological Eeports there are nine Eeports (in 12 Parts) dealing with 

 the Vertebrata ; one Eeport (in 3 Parts) dealing with the Tunicata ; 

 thirteen Eeports (in 17 Parts) dealing with the Molluscoidea and Mollusca ; 

 fourteen Eeports (in 16 Parts) dealing with the Arthropoda ; five Eeports 

 (in 7 Parts) dealing with the Echinodermata ; five Eeports (in 6 Parts) 



