26 PROCEEDINGS OF THE ACADEMY OP 



February Zd. 



The President, Mr. Lea, in the Chair. 



Nineteen members present. 



The following were presented for publication : 



Systematic arrangement of the Mollusks of the Family Viviparidae 

 and others inhabiting the United States. By Theodore Gill. 



Enumeration of the Arctic Plants collected by Dr. I. I. Hayes, 

 in his Exploration of Smith's Sound, etc. By E. Durand, T. P. James 

 and S. Ashmead. 



Mr. Cope mentioned the occurrence in the males of certain species of tree- 

 toads of the genus Trachycephalus, of a corneous thickening of the epidermis 

 of the interior metatarsus during the breeding season, similar to that in the 

 genus Discoglossus. Also, that in certain South American Bufones the manu- 

 brium sterni is present, although, up to the present time, it has been denied 

 that such is the case. 



February 10th. 



The President, Mr. Lea, in the Chair. 



Twenty-nine members present. 



Tbe following was presented for publication : 



Remarks on the North American iEgiothi. By Elliott Coues, 



Mr. Lea read part of a letter from Dr. Lewis, of Mohawk, New York, in 

 which he said that he was gratified with one thing which was not apparent to 

 him at first. In his notes on Melania subularis, Lea, and M. exilis, Hald., 

 two species of his neighborhood, he finds an evident confirmation of Mr. Lea's 

 views about Trypanosoma and Goniobasis, to which two sections of Melanidoz 

 the two species belong. The soft parts affirm the correctness of Mr. Lea's 

 generalizations from the shells. Dr. Lewis thinks the sinus in the sides of 

 subularis is peculiar, and will be found in the whole group of Trypanostoma 

 and the granular sides of exilis in the whole group of Goniobasis. It becomes 

 now a curious speculation what may be the characters of Anculosa, Schizos- 

 toma, Lithasia, Io, &c. 



Dr. Wilcocks read an extract from M. Arago's " Astronomie Populaire," 

 vol. i. p. 459 : " I have been anxious to ascertain who first noticed the ex- 

 istence of blue stars. The ancients only spoke of white and red ones. In the 

 latter class they placed Arcturus, Aldeboran, Pollux, Antares and Orionis, 

 which are still red. To this list (and the circumstance is worthy of remark) 

 they added Sirius, whose whiteness strikes all eyes. It seems, then, that 

 with time certain stars change color. The first observation (known to me) 

 made of a blue star, occurs in the Treatise on Colors, by Mariotte, published 

 in 16S6." 



Dr. Wilcocks stated that he had read the extract from M. Arago's work as 

 a preface to an observation of his own, viz.: that the star Sirius is no longer 

 white ; its present color is violet. 



If the star, instead of undergoing a single change of color in the lapse of 

 ages, should take in succession all the hues of the spectrum, it adds much to 

 the interest of the subject, and will certainly give an impetus to inquiry con- 

 cerning the cause of these remarkable changes. 



Mr. Ennis remarked that this announcement by Dr. Wilcocks appeared to 

 him deeply interesting, from the fact that for the past year he had made the 

 colored, the variable, the periodic, the lost, and the temporary stars a special 



[Feb. 



