Reviews — Brief Notices. 571 



specimens showing replacements of the incisors known, none have 

 shown any replacement of cheek-teeth, a fact which has told somewhat 

 against the relation of these types to mammals. It now seems 

 probable that the group will show us all the stages, from the indefinite 

 replacement of teeth in the ordinary reptilia to a very definite 

 replacement similar to that occurring in mammals. The specimen 

 is perhaps not absolutely conclusive, but affords very considerable 

 reasons for believing that Dr. Broom's interpretation is correct. 



6. On the Oeigik of the Cheikopterxgium. By K. Broom. Bull. 

 Amer. Mus. Nat. Hist., vol. xxxii, art. xxvii, pp. 459-64. 



A description of the well-known fin of Sauripterus taylori, and the 

 suggestion that the Tetrapod limb may have been derived from such 

 a fin by the development of some of the pre-axial skeletal elements 

 and the loss of the post-axial, which continued to support the fin 

 during the change. 



7. The Skull Elements oe the Permian Tetrapod a in the 

 American Museum oe Natural History, New York. By 

 F. V. HuENE, Tubingen. 



In this large paper the author gives short descriptions and figures 

 of mainy of the types of reptiles found in the ' Permian ' of Texas. 

 This paper is important in that it contains the views and criticisms of 

 a distinguished and independent author on many of the disputed facts 

 of structure of these very interesting forms. Dr. v. Huene not only 

 adds to our knowledge by determining many new sutures, but ahso 

 by redetermining some of the bones figured by Case. The author 

 adds some interesting discussion on morphological points and on 

 taxonomy, 



8. The Tegelen Bear. — Mr. E. T. Newton has described under 

 the name of Ursus etruscus {= V. arvernensis) a number of teeth from 

 the Pliocene clay of Tegelen-sur-Meuse (Geological Proceedings for 

 Netherlands and Colonies, 's Gravenhage, 1913). He remarks that 

 " At present U. etruscus is only known from Pliocene deposits of 

 Europe ; but there are indications of somewhat similar fossil forms 

 occurring in India and China, and it may well be that from these 

 Pliocene species the modern Black Bears are descended which to-day 

 are found widely distributed in America and Asia". 



9. Mr. Chester G. Gilbert and Mr. Joseph E. Pogue contribute to 

 the Proceedings of the United States National Museum, vol. xlv, 1913, 

 a paper on "The Mount Lyell Copper District of Tasmania ", in 

 which they gave a succinct account of the geology and mode of 

 working the famous copper-mines. The paper, which is the outcome 

 of a study of a representative collection of rocks received in 1910 

 by the museum from Mr. Eobert Slicht, manager of the Mount 

 Lyell Mining and Railway Co., is largely based upon Professor 

 J. W. Gregory's well-known memoir. 



10. In the Bulletin de la Societe Beige de Geologic, vol. xxvii, 1913, 

 M. A. Ledoux gives the results of an elaborate study of quartz 

 crystals from Belgium, and records altogether eighty-one forms. 

 Twins are very common, and, indeed, etching figures show that 



