94 MiscellaneouH. 



very distant from the coast opposite Noirraoutier (between 7° and 8° 

 W. long.), approaches it about the opening of the basin of Arcachon 

 (between 5° and 4° W. long.), and presents itself at a short distance 

 from St. Jean de Luz and Spain. The depth of the terrace at its 

 middle part is from 45 to 60 fathoms, and from 90 to 100 fathoms 

 near its western limit. 



I have received a great number of specimens from dredgiugs and 

 soundings performed on different parts of the terrace ; all of them 

 were taken several leagues out to sea (the maximum 36 leagues), 

 and at depths of 40 to 80 fathoms, under the directions of MM. de 

 Folin, A. Lafont, and some captains of ships. Thanks to these 

 supplies, I have been able to determine the species of animals which 

 live at these depths at considerable distances from the coast. 



The Mollusca form the majority, and most of them had never been 

 indicated as French, such as Necera costeUata, Desh. ; Psammobia 

 costulata, Turt. ; Lepton nitidum, JefFr. ; Lecla tenuis, Phil. ; ^drea 

 pectunculoides, Seacchi ; Lima siobauriculata, Mont. ; Scissurella 

 crispata, Flem. ; Cyclostrema nitens, Phil. ; Rissoa soluta, Forbes ; 

 Eulima bilineata, Alder; Mangelia horealis, Loven ; Mangelia eJegans, 

 Seacchi, &c. 



It was impossible, in fact, to obtain these species along our coasts ; 

 in England and Norway they are dredged at a small distance from 

 the shore, and at great depths. The existence of the submarine 

 terrace compels us to seek several leagues out to sea for the deep- 

 sea fauna ; hence the apparent poverty of the French coasts. 



English authors have remarked that a certain number of quater- 

 nary mollusca, or inhabitants of great depths in the Mediterranean, 

 are only met with again in the British seas, without presenting in- 

 termediate stations ; from this they have concluded that, imme- 

 diately before the present epoch, and at the close of the tertiary 

 period, the Mediterranean communicated with the ocean by means 

 of an arm traversing Aquitaine and Languedoc. This hypothesis, 

 which is not supported by any geological fact, seeing that the nu- 

 merous tertiary lacustrine deposits of these countries have never 

 been covered by the sea since their first emergence, is still further in- 

 validated by the result of the dredgings of the littoral terrace, which 

 clearly proves the continuity of habitat of the species formerly re- 

 garded as localized at such distant points. 



Besides Mollusca, the deposits of the terrace contain the debria of 

 Echinoderms, such as tests of Echinocyamus, spines of Echinus, 

 Spatangus, and Amphidetus, and numei'ous ossicles of Starfish. 



The Bryozoa, with the exception of branches of Salicornaria, are 

 adherent to shells ; but they live at less depths than 50 fathoms. I 

 have recognized the following species v — -Hippothoa boreaUs, D'Orb. ; 

 Hippothoa divaricnta, Lamour. ; Tubulipora serpens, Linn. ; and 

 several species of Lepralia, CeUepom, and Discoporella. 



The Foraminifcra are rather rare; there are ■.—MiJioUna bicornis, 

 Walk. ; liotalia Beccarii, Linn. ; Truncatidina lobatida, Turt. ; Pla- 

 norbulina vulgaris, D'Orb., &c. 



Lastly, I may cite some tubes of Annelida of the genera Ditrupa 

 and Serpula. 



