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



all fellow-workers, whom, in the course of the preparation of his Report, he may have 

 consulted. This is also a fitting place to record the assistance I have derived from 

 the late Dr. Gwyu Jcfi'roy's writings on the deep-sea fauna of the North Atlantic, and to 

 acknowledge his courtesy in kindly giving his opinion upon certain difficult and doubtful 

 questions. To my friend W. H. Dull, of the Smithsonian Institution, I am under similar 

 obligations. 



The name Pelecypoda given to this section of MoUusca by Goldfuss ' ought, I think, 

 to be used in preference to that of Lamellibranchiata. Not only has it priority, but, as 

 pointed out by Stoliczka, it is also more in uniformity with the nomenclature of the other 

 classes of Mollusca, the Cephalopoda, Pteropoda, Gasteropoda, &c., and points to the 

 modification of one of the most important organs — that of locomotion — of the animals. 



This class was designated Lamellibranches by Blainville ^ as early as the year 1816, 

 four years before the publication of Pelecypoda by Goldfuss, but was not characterised, 

 and the term Lamellibranchiata, accomj^auied by a description of the class, did not appear 

 until the year 1824, in Blainville's article on Mollusca in the Diet. d. Sci. Nat., vol. xxxii. 

 p. 306. It will therefore be seen that Pelecypoda, although published somewhat later 

 than Lamellibi'anches, was in reality the first to be characterised. I should also here 

 notice that Blainville imposed the name Tetrabranches upon the bivalves^ two years 

 before the invention of Lamellibranches, but, in that instance also, unaccompanied by 

 any description. The class-names " Acephala" of Cuvier and " Conchifera" of Lamarck 

 were published a year or two prior to the appearance of Goldfuss's work, but, as they 

 include groups which are regarded in modern science as distinct classes, their adoption is 

 not advisable, seeing that Pelecypoda applies only to true bivalve MoUuscs as now under- 

 stood. The name Lamellibranchiata is used in the present Eeport as it appears in the 

 several works published by Sir Wyville Thomson, Professor H. N. Moseley, and others in 

 connection with the voyage of the Challenger, also in the Narrative of the Cruise, and 

 because it had already been wTitten on some of the plates before this subject of nomen- 

 clature had been studied. 



In describing the new species I have deemed it advisable to give Latin diagnoses, as 

 practical experience has proved to me the advantage of such descriptions, and the custom 

 is adopted by continental writers almost without exception. Through long use the Latin 

 terminology has acquired a settled signification, and is generally understood, which is not 

 the case in resj)ect of other languages, and the time has not yet arrived that any one 

 particular modern language is universally so thoroughly known that its adoption as the 

 language of science can be determined upon. 



1 Handbuch der Zoologie, 1820, vol. i. p. 599. 



2 Bull. Soc. Fhilom. Paris, 1816, p. 122 ; and Journ. de Physique, 1816, vol. Ixxxiii. p. 255. 

 s Bull. Soc. Philom. Paris, 1814, p. 179. 



