158 



Messrs. Carpenter and Jeffreys on [Dec. 8, 



creased so much that, after fruitlessly endeavouring to dredge, we anchored 

 in the evening for shelter in Setubal Bay. "We there dredged, with no 

 special result. Professor Bocage had kindly given us at Lisbon a letter of 

 introduction to the coast-guard Officer at Setubal, who was said to know 

 the only place where the deep-sea Shark and the Hyalonema are taken by 

 the fishermen ; but the state of the weather unfortunately prevented our 

 availing ourselves of it. 



18. July 26th. Although the wind was rather high and the sea rough, 

 we contrived (owing to the admirable management of Captain Calver) to 

 dredge off Cape Espichel in 740 fathoms (Station 20) ; and later in the 

 day, having stood out further to sea, in 718 fathoms (Station 22.). Deeper 

 water is sometimes found to be near land than at a distance from it. The 

 Mollusca were mostly of the same kind as those from No. 1 6 (994 fathoms), 

 but included Leda pusio, Limopsis pygmcea (Sicilian fossils), and Pecchio- 

 lia acuticostata. The last-named species is extremely interesting in a 

 geological as well as geographical point of view. It is a fossil of our 

 Coralline Crag and the Sicilian pliocene beds ; and it now lives in the 

 Japanese archipelago. Some Japanese Brachiopods and Crustacea also 

 inhabit the Mediterranean. It may be difficult to account for this migra- 

 tion to or from Northern Asia, except through the Arctic ocean ; but we 

 would again venture to call attention to the suggestion made by Mr. Jeffreys 

 as to the communication which probably existed, at a period subsequent 

 to the Middle Tertiary or Miocene epoch, between the North Atlantic and 

 the Mediterranean, in the direction of the Languedoc canal or Canal du 

 Midi, from the Bay of Biscay to the Gulf of Lyons. The Straits of Gibraltar 

 do not appear to afford the means of such migration or transport of any 

 northern Fauna to the Mediterranean, because the current which flows into 

 it from the Atlantic is superficial only, and does not reach the bottom, 

 which the Pecchiolia inhabits. This Mollusk has no power of swimming, 

 like many univalves ; nor does its fry rise to the surface and become for a 

 short time oceanic, as in certain species of Trochus and Dolium. Any 

 current which flows out of the Mediterranean at its bottom into the 

 Atlantic would transport the fry of the Pecchiolia southwards, or at any 

 rate could not withstand the great northern current which brings Arctic 

 mollusca to the Lusitanian seas. Now the greatest height above the sea 

 in the line of the Canal du Midi from Bordeaux to Narbonne is stated to 

 be 189 metres, or about 615 feet. M. Reboul, in his "Memoire sur les 

 Terrains de comblement tertiaire " (Mem. Soc. Geol. de France, 1834) men- 

 tions, as to the district in question, marine tertiary shells which had been 

 deposited by a sea higher by about 200 metres than the present sea ; and 

 he says that M. Deshayes considered these shells to be among the most 

 recent of the Tertiary period. No lists of the shells, or any definite par- 

 ticulars of the deposits, however, have been published by French geologists ; 

 and it is to be hoped either that this deficiency will be supplied by them, 

 or that Mr. Prestwich may be able to investigate the matter with his usual 



