1886.] NATURAL SCIENCES OF PHILADELPHIA. 343 



Herbarium is 736. In the general collection are 570 species, and 

 in the Schweinitzian are 462. The general collection contains 

 244 species not found in the Schweinitzian, and the latter has 

 282 species not found in the former. In all, 65 genera are well 

 represented. 



In regard to the Schweinitzian collection he remarked that the 

 same species often there appeared under several names, being 

 simply in different stages of development. Genera too were 

 founded upon juvenescent stages or gonidial conditions which, from 

 the time of Acharius to that of Schweinitz and later, were con- 

 sidered sufficient to establish generic distinctions. For example, 

 such genera as Leparia, Isidium and By^tsus, were then deemed 

 valid, but are now considered to be, some of them young and 

 irioid states of plants mostly belonging to the section Lecanora ; 

 others, sterile states of Omphalaria, Ceenogonia, or other Colle- 

 matous Lichens. 



He spoke of several rare and interesting specimens in the col- 

 lection. Of these, in the Schweinitz Herbarium, is a crustaceous 

 Lichen found in 1812 at Salem, N. C, on a granitic rock, and 

 called by the collector Gyalecta Candida^ and by this name known 

 only to a few up to the year 1866. At this period Prof. Tucker- 

 man described the plant in an Appendix to his Lichens of Cali- 

 fornia as Opegrapha ontocheila, thus placing it permanently in a 

 well-established genus of gymnocarpous Lichens. This specimen 

 was the only one known until 1885 when Mr. Green found upon high 

 projecting schist rocks along the Catawba River at Landsford, 

 Chester Co., S. C, a lichen which was supposed to be new, until 

 Prof Tuckerman, just previous to his last illness, identified it 

 with that found by Schweinitz as above. Dr. Eckfeldt also re- 

 ferred to a remarkable foliaceous Lichen found near Cincinnati by 

 Mr. T. G. Lea in 1889, formerly known as Parmelia Ohionis (Lea, 

 Catal. PI. Cincinnati, p. 45), but since described by Tuckerman 

 as Physcia Leana. So far as Dr. Eckfeldt was aware, this rare 

 species had not since been found. He also referred to the diffi- 

 culties encountered in the examination of much of the material, 

 many of the types being old and fragile, having lost the parts 

 most important for study, for want of proper care. Only a prac- 

 ticed eye, aided by constant use of the microscope, and by com- 

 parison with authentic specimens, can surely determine the doubt- 

 ful and difficult forms present in this section of cryptogamic 

 botany. 



October 19. 

 The President, Dr. Leidy, in the chair. 



Twenty-seven persons present. 



A paper entitled " The Genera Mesonyx and Pachygena Cope," 

 by Wm. B. Scott, was presented for publication. 



