432 1. Gull—Number of Classes of Vertebrates. 
"The comparatively recent discoveries of immense deposits of 
coal in the Rocky Mountains makes the study of its modes of 
occurrence, its quality, and the conditions of its formation, a 
subject of great economic and scientific interest, which it is 
desired to present in the most satisfactory manner. For this 
purpose, specimens from all of the important outerops — 
our route have been carefully obtained, and minutely record 
Having some opportunities for observation and study of the 
language, manners and customs of Washakie’s band of Sho- 
shones or Snake Indians, I was enabled to collect also a few 
notes, which may serve, in a small way, to assist in preserving 
some records of their peculiarities, ere the onward mare 
civilization shall forever, by conquest or assimilation, destroy 
their dndian charateristics. All of these subjects, when prop- 
erly elaborated, will be incorporated in my report to the chief 
of the expedition, to be given to the public in due time. 
In conclusion, my thanks are due to each member of the 
party, including the officers of our escort (Company I, 2nd U. 
S. Calvary) and to the officers and others at Fort Bridger, 
Camps Stambaugh, Camp Brown and Fort Ellis, to whom Jam 
indebted for kindnesses too numerous for recita 
Cherishing the hope that my humble labors in the cause of 
science may prove of some value to others, I leave this resumé 
in the hands of my fellow-workers for their verdict. 
Cleveland, O., Oct. 25, 1873. 
Art. XLVIUL—The Number of Classes of Vertebrates and their 
utual Relations; by Prof. THEODORE GILL. 
(Abstract of a Communication to the National Academy of Sciences made Oct. 
29, 1873.) 
on land (Quadrupeds) ; (2) those especially fitted for progress! 
through the air (Birds); and (83) those adagned for life 
It was, therefore, a great advance when Linnzus established @ 
