98 



regard tLem as older. They must be subordinate to the Potsdam, 

 and will represent the true primordial zone in Canada. The strata 

 at Georgia he considers a constituent part of the primordial zone. 

 He thought that the Huronian system of Mr. Logan Avas not a good 

 one ; it contains no fossils, and it is impossible to define its commence- 

 ment or its end. 



Prof. B. Silliman, Jr. observed that the geologists who differed 

 from Mr. Marcou in regard to the cretaceous rocks of Texas were 

 accomplished and conscientious observers, who had sent to Washing- 

 ton a large collection of fossils, which would probably throw light 

 upon the disputed points. The March number of Silliman's Journal 

 would contain a section of the district made with great care by Dr. 

 Shuraard. He observed that the Canadian geologists still adhere to 

 their original account of the rocks at Montmorenci. 



Dr. Qould remonstrated against the recent misrepresentations of 

 some English naturalists in regard to the specific distinctness of faunae 

 far removed from each other; they pretended that he and other 

 American naturalists set down everything found at a distance as 

 prima facie a distinct species. He was not aware that any naturalist 

 maintained such a proposition, but he would say that species far 

 removed from each other, without any plausible means of connection, 

 are probably distinct. There are some species of animals, as cer- 

 tain helices, which ai'e more or less cosmopolite ; but these are few, 

 and the tendency of recent examinations in all departments of the 

 animal kingdom is to show that most supposed identical species in 

 faunae far removed from each other are really distinct, and that the 

 supposed different species which are really the same are very few. 



Dr. White exhibited a mouse whose head was almost 

 entirely covered by large masses of the j^arasite fungus 

 Achorio7i Schoenlinii. 



The growths formed dry, yellowish crusts resembling in shape ker- 

 nels of popped-corn. Nothing of the head was visible with the ex- 

 ception of the ears and mouth. This animal was one of twenty or 

 thirty caught during the past three months in the seed-store of Curtis 

 & Cobb, in this city, nearly all of which have had more or less of the 

 same appearance. Even the young have exhibited it, when they 

 belonged to mothers similarly affected. They were all killed by a 

 cat. As is well known, this parasitic plant is the cause of the disease 

 upon the human scalp known as Favus, which is characterized by the 

 appearance of crusts exactly similar to those seen upon the mouse, 

 and by the loss of hair. These crusts consist of minute sporules and 

 sporangia, that is, the reproductive portion of the fungus, together 

 with a slight growth of the mycelium. These spores coming in con- 



