348 TRANS. OF THE ACAD. OF SCIENCE. 
sey seems to have undergone but slight metamorphic 
change. The fossils obtained “here are chiefly Productus 
costatus. ‘The thickness of the strata, as well as could be 
gradually ascended to the summit of the mountains where 
night overtook us, and we were, for the first time since leay- 
ing Dofia Ana, obliged to camp without water. oe 
ture at 12 o’clock P. M., 8° F. 
The height of our evening camp, as determined by barome- 
trical measurements, was found to be one thousand seven 
hundred and eighty-one feet above Dofia Ana, and five 
thousand six hundred and fifty-eight feet above the level of 
the : sea. 
_ Dee. 16. At a little distance from our last evening’ cam 
Ca reonated 
