PROCEEDINGS. LI 



an attempt to again return to the ancient isocercal form of the 

 vertical fins. 



Mr. C. D. Walcott exhibited a specimen of trilobite, Asaphiis 

 platycephalus, in which twenty-six pairs of legs were plainly seen, 

 no mouth parts being visible. These were shown by a drawing 

 illustrating Mr. Walcott's restoration of the mouth appendages of 

 the trilobite, as pubHshcd by him in the Bulletin of the Museum of 

 Comparative Zoology, Vol. VIII, No. lo, 1881. The specimen 

 was the same as that described by Prof. Mickleborough, of Cincin- 

 nati.'i^ Mr. Walcott also showed a specimen of metamorphic rock 

 having a granitic structure and containing fossil corals, probably of 

 the Devonian age. 



Prof. L. F. Ward moved that the meeting day of the Society be 

 changed to Saturday. After remarks by Dr. Baker, Dr. Coues, 

 and others, the motion was carried by a unanimous vote. 



Fifty-Eighth Meeting, February 23, 1884. 



The President occupied the chair. Thirty-six members were 

 present. 



Dr. Elliott Coues read a paper on The Present State of North 

 American Ornithology. In discussing the precontemporaneous 

 history of the subject, he spoke of the following epochs : — 



(i) The Archaic (prior to 1700); (2) the Pre-Linn^ean (1700- 

 1758); (3) the Post-Linnaian (1758-1800); (4) the Wilsonian 

 (1800-1824); (5) the Audubonian (1S24-1853) ; (6) the Bairdian 

 (1853-18 — ). A number of periods were also defined as follows: 

 (i) the Lawsonian period (i 700-1 730), named after Lawson, the 

 author of the first American faunal list, that for North Carolina; 

 (^2) the Catesbian period (i 730-1 74S), named after Mark Catesby, 

 the first to publish an illustrated work on American birds; (3) the 

 Edwardsian period (i 748-1 758), named after George Edwards, 

 whose great work on birds was founded largely upon American 

 material; (4) the Linngean period (i 758-1 766), the period during 

 wliich the binomial nomenclature was being developed; (5) the 



* 1884. Walcott, Charles D. Appendages of the Trilobite. <Science, 

 III (No. 57), pp. 279-81, 1884. 



