207 



Mollusks with few exceptions, some Echinoderms, &c. In the 

 Med 1 see and Polyps, instead of chyle, chyme mixed with water 

 is circulated ; this circulation is found in some Mollusks and 

 intestinal worms; it may be seen plainly in Beroe. Prof. 

 Agassiz thinks that the embryological development of the higher 

 animals shows a similar succession in the circulating function. 

 He also examined the connection of respiration with the circula- 

 tion ; in Vertebrata, the gills are found between branches of the 

 blood system ; in Invertebrata, the chyliferous system is acted 

 on by the respiration ; the gills of fishes, then, cannot be com- 

 pared to the gills of Crustacea, Articulata, and Mollusks. No 

 gills are connected with the chymiferous circulation ; animals 

 having this circulation have no true respiration ; they have only 

 tubes to distribute freshly aerated water to the different parts of 

 the body. 



Mr. Desor alluded to a fine skeleton of a Mastodon, 

 which he had lately seen at Galena, Mo., taken from the 

 depth of seventy feet. 



It has been thought that this specimen is from the true drift ; 

 but it was found in a deposit mixed with drift materials, which he 

 considered subsequent to the true drift. This is not, therefore, 

 a clear instance of the Mastodon in the drift. In reply to a 

 question from the President as to the size of the skeleton, he 

 remarked that one of the tusks was three inches in diameter, and 

 must have belonged to a large animal ; the teeth were fine. 



Mr. Desor also made some remarks on the sand dunes of 

 Lake Superior, which were first brought into notice by Mr. 

 Schoolcraft. 



According to him, some of these dunes are three hundred and 

 fifty feet high. They are not formed like those at Province- 

 town, but belong to the true drift ; there is a clear line of 

 demarcation between the drift sand and the red clay. The 

 whole ground was once covered with trees, which, having been 

 removed probably either by wind or water, the sand has been 

 blown to the eastward by the prevailing northwest wind, forming 

 dunes about four miles below the present limit of the wooded 

 clay. The Grand Sable is three hundred and fifty feet high. 



