284 PROCEEDINGS OF THE NATIONAL MUSEUM vol.83 



the more impervious clays collects and yields water during the moist 

 seasons. It appears unlikely that the animals were transported 

 by water any distance after death but accumulated naturally around 

 a water hole, aided possibly by bog trapping. There is no certain 

 evidence of trapping, as in many places the depth of the fossiliferous 

 lens b«tween the underlying clay and the stratified, undisturbed 

 -overlying sand is hardly sufficient. Erosion, however, m.ay have 

 removed a portion of the zone, although tliis is not evident. At the 

 periphery of the lens the bones extend into the unstained or less 

 colored sand but in a more restricted zone, and in places on the south 

 slope of the hill occur in a concretionary layer with a considerable 

 portion of the material firmly cemented in large blocks of gray to 

 white limy sand. 



The bone material occurring in the more pervious red sand has to 

 a large extent been affected by plastic distortion in which the bones, 

 particularly in many of the skulls, have been warped and bent. 

 Material, however, obtained in the hard concretionary patches is 

 less distorted but prepared only with considerable time and labor. 



The material collected in and about the principal quarry during 

 the four seasons of work includes over 130 skulls and a large quantity 

 of other skeletal material, some of wliich was discovered in a position 

 of articulation. About a quarter to a third of the skulls include lower 

 jaws, and 8 or 10 specimens are comprised of the greater part of the 

 skeleton. 



ASSOCIATED FAUNA AND ENVIRONMENT 



Contemporary with Plesippus shoshonensis in the Hagerman lake 

 beds was a large fauna including fishes, amphibians, reptiles, and a 

 variety of birds and mammals. Remains of these animals were 

 found at various localities witliin a distance of about 9 nules to the 

 south of the quarry, a number being also represented in the quarry 

 internnngled with the horse bones. The following is a list of the 

 vertebrate forms known to occur in the Hagerman lake beds: 



