1882.] 
306 
[January 4, 
Thus we see that the number of phalanges is least, and the 
claws are absent, in what are usually considered the highest 
groups of birds. Even in the case of some of the groups of the 
Picariae, where the hand is very large and the forearm and arm 
very small, this is true. In going down the series, the first thing 
we meet is a two-jointed thumb provided with a claw, the second 
finger having only two joints, at least in the adult. Near the bottom 
of the scale we find birds with a two jointed-thumb and a three- 
jointed second finger, though Nitzsch’s statement that a claw is 
always present when three joints occur in the second finger, is 
wrong. Nitzsch was not aware of the common occurrence of the 
third phalanx among the water birds. At the bottom we find the 
ostrich with a two-jointed first finger. 
The number of phalanges and the presence of claws is of value 
as affording points of difference and resemblance in one of the, so 
to speak, most conservative organs of the group, the wing. They 
also make it unadvisable to put birds with a complete phalangeal 
schedule as descendants of those with an imperfect one, as has 
several times been done. 
Dr. M. E. Wadsworth referring to the lithology of Marble- 
head, remarked that the well known country rock of this locality 
had been variously known as greenstone, syenite, diorite, etc. 
Microscopic examination proved that it is an augitic rock, a 
true diabase, as the speaker had suspected from its physical 
characters. It is closely like some of the Somerville diabases 
described by him before this Society in 1877. 
General Meeting. January 4, 1882. 
The President, Mr. S. H. Scudder, in the chair. Forty-three 
persons present. 
The following were elected Associate Members. 
Mr. Edgar N. Williams, Mrs. Ellen H. Richards, Miss L. M. 
Hill, Mr. Nathan Frederick Merrill, Mr. John Dane, Mr. Ralph 
Stockman Tarr, M. H. Richardson, M. D., Mr. Edmund M. 
Haskell, Miss J ennie Smith, Mr. Alvin A. Bragden, Miss C. Ade- 
laide Studley. 
