130 REMAKES ON THE GEOLOGICAL DISTRIBUTION 



of specimens. From this valuable memoir are derived a few notes which 

 complete what the paleontologist may wish to know in regard to the strata 

 from which the fossil remains are derived. 



Professor Scudder's memoir is elucidated by a map of the Tertiary 

 basin of Florissant as it was at the time when the strata were deposited. 

 The area was then covered by a shallow sheet of water, hemmed in on all 

 sides by near granite hills whose wooded slopes come to the waters edge, 

 sometimes, especially on the northern and eastern sides, rising abruptly ; at 

 others gradually sloping so that reeds and flags grew in the shallow water 

 by the shore; the water of the lake, penetrated by deep inlets between 

 the hills, giving to it a varied and tortuous outline. This old lake was 

 really a long outlet following the bottom of the valley, and expanding on 

 both sides in lateral long shallow straits or pools. In one place the lake 

 is contracted to half a mile in width ; at two others one-fourth of a mile ; 

 taken altogether it is on an average 1 mile broad, being 6 to 7 miles long, 

 expanding, on the eastern side especially, into nine of those narrow shal- 

 low straits. The outlines of the straits are, of course, varied. The area 

 covered by their water measured half a mile to a mile long, one-fourth to 

 half a mile broad, so that the shape of that Tertiary lake, as it is repre- 

 sented upon the map, resembles an oblong leaf, lobate on the borders, 

 somewhat like a leaf of the white oak. It is easy to understand how those 

 shallow pools, penetrating between hills covered with deep forest, alter- 

 nately drying in summer and filling up in the rainy season, could become 

 the reservoirs of woody and animal debris thrown upon their surface from 

 overhanging trees and rocks, and there periodically accumulating by the 

 succession of dryness and flood. 



Professor Scudder supposes that the ancient outlet of the whole 

 system was at the southern extremity; at least, the marks of the lake 

 deposits reach near the ridge which now separates the waters of the Platte 

 and of the Arkansas; and the nature of the basin itself, the much more 

 rapid descent of the present surface on the southern side of the division, 

 with the absence of any lacustrine deposits upon its slopes, lead to this 

 conclusion. 



Says Professor Scudder: "The very shales of the lake itself, in which 



