240 SCIENCE PROGRESS 



the Indians of Guiana," which appears in the Rationalist Press 

 Association Annual for 191 8. 



PALAEONTOLOGY. By W. P. Pycraft, F.Z.S., A.L.S., F.R.A.I., British 

 Museum (Natural History), South Kensington, London. 



Having regard to the times, surprise can scarcely be felt at 

 the fact that there is little to record in regard to fossil animals 

 for the first six months of 191 8. 



Dr. Branislaw Petronievics {Ann. and Mag. Nat. Hist. 

 pp. 67-69, 191 8) gives a brief account of the results of a re- 

 examination of the lower jaw of that primitive and remark- 

 able mammal Stereognathus ooliticus, preserved in the Museum 

 of Practical Geology. Marsh, years ago, contended that this 

 fragment represented, not the lower, but the upper jaw. Dr. 

 Petronievics received permission to convey the specimen to 

 the British Museum of Natural History, for the purpose of 

 removing more of the matrix, and, as a result, he has been 

 enabled to show that Owen was right in his determination 

 of the nature of this jaw, but inaccurate in regard to his 

 description of the teeth. The oblique position of the cusps of 

 these, he believes, is due to the motion of the lower jaw from 

 behind forwards, a movement which he mistakenly supposes 

 to be opposite to that which obtains among rodents. In an 

 earlier paper which appeared in this Magazine (pp. 284-9, 

 191 7) too late for mention in my last summary, the author 

 describes anew the skull of that remarkable mammal Tritylodon 

 longawus, originally described by Owen. Many new features 

 of importance are established as a consequence of this re- 

 examination. He disposes of the view which has been held 

 that this skull is that of a theromorphous reptile. Its mam- 

 malian characters are, he insists, beyond dispute ; but it is 

 to be regarded as the most primitive of known mammals ; 

 and furthermore affording direct proof that the mammals have 

 their origin in Reptiles, most probably in Theriodont Reptiles. 



Mr. Lawrence M. Lambe {Canada Dep. of Mines, Geol. 

 Survey, No. 53, Geol. Series, pp. 2-84, 191 7) discusses the 

 Cretaceous Theropodous Dinosaur Gorgosaurus. The skeleton 

 of this remarkable creature is described with great care, and 

 the memoir concludes with a discussion on the supposed 

 appearance and habits of the animal during life. That it was 



