5o6 



THE POPULAR SCIENCE MONTHLY. 



from the divers or owners of diving-appa- 

 ratus. In this way the article may be got 

 at first hand, without being weighted with 

 sand. 



Alligators swallowing tlicir Yonng.— Col- 

 onel Caleb G. Forshey, of the New Orleans 

 Academy of Science, d propos of the ques- 

 tion whether snakes swallow their young, 

 states that this habit is certainly found 

 among alligators. " That alligators swallow 

 their young," says Prof Forshey, " I have 

 had ocular demonstration in a single case ; 

 and have the universal tradition of negroes 

 and whites in this region of Louisiana, Mis- 

 sissippi, and Texas, that such is their habit. 

 In the winter of 1843-'44, I was engaged 

 making a survey on the banks of the Homo- 

 chitto Lake. The day was warm and sunny, 

 and, as I halted near the margin of a pond 

 partly dried up, to pick up some shells, I 

 started a litter of young alligators, that 

 scampered oflf, yelping like puppies, and re- 

 treating some twenty yards to the bank of 

 Lake Homochitto. I saw them reach their 

 refuge in the mouth of a five-foot alligator. 

 She evidently held open her mouth to re- 

 ceive them, as, in single file, they passed 

 in beyond my observation. The dam then 

 turned slowly round, and shd down beneath 

 the water, passing into a large opening in 

 the bank, beneath the root of an ash-tree. 

 Doubtless this refuge is temporary, and the 

 young are released at their own or the 

 mother's pleasure." 



Le Conte on the Origin of Western 

 Monnds. — Prof Joseph Le Conte, in the 

 American Journal of Science^ discusses 

 the origin of the mounds with which the 

 prairies near Puget Sound are studded, and 

 from which they get the name of "mound 

 prairies." These mounds are generally three 

 or four feet high, and thirty to forty feet in 

 diameter at the base. There are millions 

 of them, and they stand so thickly as to 

 touch each other at their bases, leaving no 

 level space between. They consist wholly 

 of a drift-soil of earth, gravel, and small peb- 

 bles, the intervals being thickly strewed with 

 larger pebbles and small bowlders. The 

 vegetation of the mounds is mostly ferns; 

 the intervals are covered with fine grass 

 only. Some have supposed that they are 



Indian burial-mounds ; others have thought 

 that they are artificial mounds, upon which 

 were built huts of Indian villages. They 

 have also been supposed to be large fish- 

 nests, dating from the period when these 

 prairies were the bottoms of shallow inlets 

 of the sea. The author holds them to be 

 the result of surface-erosion under peculiar 

 conditions. In another part of the State, 

 viz., between the Dalles and the upper bridge 

 of the Des Chutes River, a distance of about 

 thirty miles, the whole country is literally 

 covered with mounds of this kind. Here 

 they vary in size^ from scarcely detectible 

 elevations, to mounds five feet high and 

 forty in diameter at the base; and mform 

 from circular, through elliptic and long ellip- 

 tic, to ordinary hill-side erosion-furrows and 

 ridges. In regularity of size and position 

 there is equal diversity ; in some places be- 

 ing as complete as at Mound Prairie, while, 

 in other places, they are of different sizes, 

 and often separated by wide^ pebble-covered 

 spaces, as if they were but the remnants of 

 a general erosion of the surface-soil. No 

 one, says Prof Le Conte, can ride over those 

 thirty miles, and observe closely, without 

 being convinced that these mounds are 

 wholly the result of surface-erosion, acting 

 under peculiar conditions. These condi- 

 tions are, a treeless country, and a drift-soil, 

 consisting of two layers — a finer and more 

 movable one above, and a coarser and less 

 movable one below. Surface-erosion cuts 

 through the finer superficial layer, into the 

 pebble-layer beneath, leaving, however, por- 

 tions of the superficial layer as mounds. 

 The size of the mounds depends on the 

 ihichuss of the superficial layer ; their shape 

 depends much on the slope of the surface. 

 The process once started, small shrubs and 

 weeds take possession of the mounds, as 

 the better soil, and hold them by their roots, 

 and thus increase their size, by preventing 

 or retarding erosion. The treelessness of 

 Eastern Oregon has been produced gradu- 

 ally, since post-tertiary times, by the in- 

 creasing dryness of the climate. We may 

 imagine the mounds, therefore, as having 

 been held by the struggling remnants of a de- 

 parting vegetation. At Mound Prairie, how- 

 ever, the treelessness is probably produced 

 by a contrary condition, viz., the extreme 

 wetness of these lower level spots in winter. 



