166 Report of the Researches of M. Agassiz. 



In conclusion, I would sum up the subject by saying that the normal 

 position of the acephalous mollusca is vertical, the tubes being above 

 and the mouth below, in all symmetrical bivalves ; whereas it is horizon- 

 tal, the mouth on the one side and the anus on the other, in all unsym- 

 metrical shells. In the first case we have a right valve and a Irft valve, 

 and in the other an upper valve, and a lower valve. This normal position 

 being the natural one to adopt, and capable of conferring great advan- 

 lages on geological observations relative to the condition of the seas at 

 different epochs and at different parts of a basin, I intend to retain it 

 scrupulously in the representation of all shells ; and, as it has been sub- 

 mitted to the test of numerous observations made in all latitudes, geolo- 

 gists may confidently rely on its accuracy, and compare the state of 

 the faunas contained in the strata composing the crust of the earth.* 



Report of the Researches of M. Agassiz during his last two 

 sojourns at V Hotel-des-Neuchatelois^ upon the Lower Glacier 

 of the Aar, in the gears 1841 and 1842. By M. E. Desor. 



The importance which the study of the glaciers has lately 

 acquired, is so generally known, that but few words are neces- 

 sary to recommend it to the attention of the public"; and geo- 

 logy, in assigning to their influence so marked an agency in 

 the resolutions of the globe, has suddenly raised them from the 

 neglect in which they had long lain. The activity displayed in 

 these investigations has been very much spontaneous, and almost 

 universal ; for there are few countries in which the new science 

 has been put into requisition, in which the consequent observa- 

 tions have not led to the most satisfactory results. Recognising 

 a development so extensive, I fear lest the researches, of which 

 I purpose to give an account, will scarcely appear inviting, 

 owing to the contracted locality to which they refer. Many, 

 upon reading the title of this article, will, no doubt, enquire 

 what so extraordinary is to be observed and studied in the gla- 

 cier of the Aar ; so that there was occasion to resort thither 

 for two successive seasons, and remain for weeks and months 

 together. To meet all prejudices of this kind, and enable the 

 reader to judge for himself, I shall first, in a few words, give a 

 view of the state of our knowledge at the close of the year 



* AnnaU$ det Sciences NaiurdUs. Avril 1843, p. 21 2. 



