24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I03 



The fire pit, measuring 2 feet (61.0 cm.) by 3 feet (91.4 cm.), 

 had no lining. It contained charcoal, ashes, splinters and fragments 

 of charred bone, several vertebrae, one of which showed the effects 

 of fire, and a calcaneum. The vertebrae and calcaneum are from 

 the American antelope or pronghorn (Antilocapra) ,^ There was 

 an additional fire pit nearby, and a few bones from modern bison '^ 

 were found in the vicinity, but no other cultural material was 

 recovered. 



MOLLUSKS 



Numbers of mollusk shells were found in the digging, and in order 

 that there would be sufficient material for comparative purposes, 

 specimens were collected from typical wet-weather lakes in the area 

 surrounding the site. Others were gathered from shallow depressions 

 where sand and surface soil had been blown out by wind action. 

 These shells were sent to Dr. Frank C. Baker, University of Illinois, 

 who reported that the collection contained a number of land and 

 fresh-water species. Commenting on the collections Dr. Baker 

 writes : * 



The species of Ilelisoma from the pits and fossil deposits are the same as those 

 living in the Recent fauna; none are extinct, as is the case among some of the 

 vertebrates. The other species of land and fresh-water mollusks are also the 

 same as typical members of the Recent fauna. This difference in geological 

 faunal contents has been observed in many other places and is to be noted 

 especially in some Pleistocene deposits where the mollusks show little change 

 in form while the vertebrates, principally the mammals, contain several species 

 now extinct. 



It is interesting to note, although there may be no particular sig- 

 nificance in the fact, that all the shells from the excavations around 

 the basin are from a single, fresh-water species {Helisoma tenue 

 sinuosmn Bonnet) common in New Mexico, Arizona, Texas, and 

 northern Mexico. Dr. Baker states that the form is "Usually named 

 tenuis but it is a distinct race of the typical tenuis which is confined 

 to Mexico, the types being described from the vicinity of the City 

 of Mexico." The fact that the material from the basin represents 

 a fresh-water species is additional corroboration for its having been 

 a lake or series of ponds. 



^ Identified by Dr. David H. Johnson, assistant curator, division of mammals, 

 U. S. National Museum. 



^ Bones identified by Dr. C. L. Gazin, assistant curator, division of vertebrate 

 paleontology, U. S. National Museum. 



8 Letter to Dr. Paul Bartsch, curator, division of mollusks, U. S. National 

 Museum. 



