382 



EErOET — 1880. 



shallow-water excursion, while Nncula corluloules, SipJiodentalium Olivi, 

 Rissoa deliciosa, and Defrancia hispidula occurred only in tlie deep-water 

 cruise. 



The list of MoUusca will show that several species are sujiposed to 

 have been drifted from shallow water. This may have been owing to 

 the proximity of the coast and to the consequent action of rivers and 

 tides. 



Several deep-water species of Mollusca occurred in this expedition 

 which had been until lately supposed to be extinct ; they are fossils of the 

 Upper Tertiaries of Europe.^ 



A curious provision of Nature — if we may in these philosophical days 

 use such a phrase — was observable in the case of a deep-water mussel of 

 considerable size, which I propose to name Mytihis luteus. It inhabits the 

 layer of mud which I have above described, and moors or fixes itself by 

 means of a large and densely matted byssus which is spun by the foot. 

 This byssus is capable of being spread over a considerable extent of sur- 

 face ; and it not only prevents the mollusc sinking into the soft mud and 

 being smothered or buried alive, but enables it to feed comfortably on the 

 innumerable animalcute which swarm on the surface of the sea-bed. It 

 is to some extent of the same use to the mollusc as a snow-shoe is to the 

 Arctic traveller. This sjiecies of Mytilus I at first took to be the Modiola 

 incurvata of Philippi = M. MartorelU of Hidalgo— which lives on the south 

 coast of Spain in rather shallow water ; but on comjiarison I am satisfied 

 that they differ essentially in shape, sculpture, colour, and epidermis. 



I cannot conclude this account without tendering my most grateful 

 acknowledgments to the French Government for their extremely generous 

 conduct, and for the excellent hospitality which I enjoyed on board the 

 TravaiUeur, as well as to the President and members of the Scientific 

 Commission for their obliging and friendly companionship. 



The zoological results of this French expedition are fully equal to those 

 obtained by Capitaine Baudon in 1801, M. d'Urville in 1829, the Ee- 

 cherche in 1835, the Bonite in 1836 and 1837, the Astrolabe in 1841, and 

 other expeditions ; and I sincerely hope that a further expedition of the 

 present kind may take place next year in the Mediterranean, where our 

 good and gallant neighbours hp^ve such an important stake. 



A List of the Mollusca procured during the cruise of the TravaiUetir in 



the Bay of Biscay, 1880. 



' For the geological definition of this term see Jititish Concliology, vol. i. pp. 315 

 and 310. 



