291 



is caused by the action of the air introduced through the trachegs 

 upon the fat, a slow combustion, as suggested by Matteucci. 

 The light was found to continue two or three minutes after the 

 death of the animal. Dr. Burnett said that his observations on 

 this insect corresponded with his observations made several 

 years since on the common Lampyris or Fire-fly. 



Mr. Desor alluded to the fact that certain species of crabs are 

 luminous. In these this property is probably due to the nervous 

 system. 



Mr. Desor called the attention of the Society to the subject of 

 the Terraces of Lake Erie. He said that Mr. Lyell had de- 

 clared that he could not determine whether these terraces were 

 of fresh or salt water origin. With reference to this point, Mr. 

 Desor read a letter from Mr. Charles Whittlesey of Cleaveland, 

 Ohio, and another from Mr. J. A. Lapham of Milwaukie. 

 Mr. Whittlesey writes, — '-The blue marly clay of Lake Erie, 

 is, I think, of the age of the Loess of the Rhine ; for I have ten 

 shells from it at this place, about fifteen feet above the Lake 

 and a Planorbis and a Helicina, the same which I saw in the 

 Loess of St. Louis, and of New Harmony, Indiana, in great 

 abundance, the characteristic shells of the Loess of the Rhine." 



Mr. Lapham also writes to Mr. Desor, that during an expe- 

 rience of twenty years as an engineer in Ohio and Wisconsin, 

 he had never found true drift fossils in the drift deposits of the 

 Western country. " Milwaukie is surrounded by hills composed 

 entirely of drift from fifty to one hundred feet high, bordering a 

 comparatively level plain, on which much of the city is built. 

 The several streets cutting these hills have to be graded down, 

 sometimes to the depth of thirty or forty feet, and 1 have exam- 

 ined all these deep cuts anxiously for fossils or other facts bear- 

 ing on the subject, but no fossils were found. Once it was 

 reported that, in grading Vliet Street, trunks of trees, horns of 

 deer, &c. were found twelve feet below the surface ; but this 

 proved, on examination, to be the site of an ancient pond or 

 marsh, now almost entirely filled. The materials in which 

 the timber and horns were found were peat and marl, but not 

 drift, although surrounded by true drift. Upon excavating a 

 bluff near the Menomonee for the Milwaukie and Mississippi 

 railroad, a bank of sand and gravel in quite regular layers was 

 found resting against the bluff and filled with shells of species 



