DESCRIPTIONS OF EIGHT NEW SPECIES OF FOSSIL 

 TURTLES FROM WEST OF THE ONE HUNDREDTH 

 MERIDIAN. 



By Oliver P. Hay, 



Of Washington, District of Columbia. 



The new species of fossil turtles described on the following pages 

 were collected during the summer of 1900 by members of the U. S. 

 Geological Survey. Dr. T. W. Stanton, Mr. M. R. Campbell, and 

 Mr. W. R. Calvert, working in Upper Cretaceous areas whose de- 

 posits are quite certainly equivalent to the Lance (Ceratops) beds of 

 Wyoming, discovered the remains here described as Basilemys />rse- 

 clara and Aspideretes amnigenus. Mr. J. H. Gardner discovered, in 

 the Ignacio quadrangle, La Plata County, Colorado, the complete 

 plastron named below Alamosemys annexa. It seems uncertain to 

 what formation the beds belong, but this turtle indicates that they 

 are the equivalent of the Torrejon deposits of New Mexico. Later 

 in the season, Mr. Gardner, accompanied by Mr. J. W. Gidley, of the 

 U. S. National Museum, spent two days in the vicinity of Ojo Alamo? 

 San Juan County, New Mexico. In this region they found two' dis- 

 tinct formations. In the lower, composed of sandstones, clays, and 

 a bed of conglomerate, there were found fragmentary remains of 

 dinosaurs and the turtles below described as Basilemys nobilis&nd 

 Adocus vigoratus, together with considerable parts of Aspideretes 

 vorax'l and unidentifiable fragments of other Trionychidse. These 

 beds are probably the equivalents of the Lance Creek beds. Above 

 these dinosaur-bearing deposits came a deposit of conglomerate, about 

 12 feet thick at most. Succeeding this are other beds of sandstone 

 and clay, in which were found no remains except those of the turtles 

 described below as Compsemys vafer and Hoploc/tehjs bicat'itiata, and 

 probably Compsemys parva. It is possible, however, that the last- 

 named species belongs to the older beds. It is believed that the 

 deposits above the upper bed of conglomerate belong to either the 

 Puerco or the Torrejon. It must be noted that Ojo Alamo is not 

 more than about 100 miles from the Ignacio quadrangle in Colorado. 



Proceedings U. S. National Museum, Vol. 38— No. 1747. 



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