292 



SCIENCE 



[Vol. LVI, No. 1446 



It is clear also that the temi Gobi fonnation 

 or Gobi series is properly applied to the Ter- 

 tiary beds instead of to those of Cretaceous age. 



The best exposures of this underlying Cre- 

 taceous formation are in the vicinity of the 

 small salt marsh Iren Dabasu, where a total 

 thickness of about 150 feet of nearly hori- 

 zontal strata is judged to be of this age. Ter- 

 tiary beds not older than the Miocene lie on 

 top of the Cretaceous strata and are best ex- 

 posed about five miles south of Iren. Twenty 

 miles farther south early Tertiary beds were 

 found in essentially the same relation. 



The finding of this upper Cretaceous forma- 

 tion makes a new designation necessary. For 

 this purpose nothing seems to be as appro- 

 priate as the name of this locality. We there- 

 fore propose the term "Iren Dabasu forma- 

 tion" for these beds. 



Remains in all three beds are fragmentary, 

 decidedly so in the Houldjin gravels, but they 

 are of unusual interest apparently and we 

 have taken everything which has any char- 

 acter. 



Dinosaurs are represented in the Iren 

 Dabasu beds by one complete tibia, ends of 

 femora and humeri, presacral and caudal 

 centra, many good foot bones, including claws 

 of fore and hind feet, portions of a small car- 

 nivorous dinosaur skull with two or three 

 teeth, and two teeth of a predentate, as well 

 as two portions of jaw with the alveoli of 

 some teeth, also predentate. Remains of the 

 small Ornithomimus-like creature are particu- 

 larly abundant and the last day at Iren Dabasu 

 we picked up probably fifty good foot bones 

 and centra from two or three knolls. We could 

 find no teeth of the little fellow though — 

 wonder if he was edentate like Struthio- 

 mimusf The Cretaceous exposures are very 

 limited so far as we could see but may, of 

 course, outcrop in other basins to the east or 

 west of the road. We did not have time to ex- 

 tend our work in either direction. The out- 

 crops we did see will stand a more careful 

 going over. 



The Houldjin gravels are exposed as a 

 rather thin capping to a low bench of Cre- 

 taceous which we followed for several miles. 

 Things are badly broken up here — even such 

 massive bones as the heads of femora and 



humeri were usually cracked into several pieces 

 before deposition. There is one fine bone — a 

 ealeaneum of the big beast which would be a 

 match for the astragalus of Baluchithe- 

 rium- ( ? ) . I can think of nothing else to 

 which it might belong. It is as long as the 

 great Megatherium ealeaneum from Long 

 Branch, N. J., but is not edentate. A head of 

 a femur is the size of one's head and other 

 limb bone ends eoiTespond. Some enormous 

 rhinoceros teeth (broken) may belong with this 

 animal. Smaller teeth are surely Rhinoceros. 

 We did not explore the full length of the ex- 

 posure and there are possibilities in excava- 

 tion at one or two points of the blujffi where 

 we did explore. 



The Irdin Manha beds offer the greatest op- 

 portunity for future work. Mammalian re- 

 mains are abundant though fragmentary and 

 we examined less than two miles of a line of ex- 

 posures extending many miles both east and 

 west of the trail. A small lophiodont (Helaletes- 

 like) is most abundant and we got numerous 

 teeth besides two masillse (one with premaxilla 

 and orbital region) and a few lower jaws, also 

 numerous foot bones, limb bones and verte- 

 brae. Next in abundance is a perissodactyl, 

 looking much like our late Eocene titanotheres. 

 We have several premolars, many incomplete 

 molars and one lower jaw with p„ — m.^ in fair 

 condition. Other forms are curiously rare, a 

 creodont lower jaw and an artiodaetyl astraga- 

 lus or two being the only things noted. Trion- 

 ychids are common and we saw a complete 

 though badly broken carapace which we were 

 hurrying to get to our car before a storm over- 

 took us the last day we were there. We made 

 three trips down from Iren Dabasu camp but 

 could not do more as our food was getting 

 short and we had to join the rest of the party 

 here. 



In the vicinity of the small salt lake Iren 

 Dabasu, the Cretaceous beds lie immediately 

 on the slate fioor of the basin and between this 

 base and the first determinable beds of later 

 age, in this ease late Tertiary, about 150 feet 

 of strata are exposed. The bottom members 

 are dominantly sands and sandstones, prevail- 

 ingly thin-bedded, some of which are strongly 



- A gigantic perissodactyl described by C. 

 Forster Cooper from Baluchistan. 



