Notices of Memoirs — BihliocjrcqiJtij of Mexican Qeolorjij. 173 



4. Grey, extremely hard limestone, enclosing a bed of greenish- 

 grey, argillaceous limestone, with well-preserved specimens of Spirii/era 

 Mmizavinti, Bittn., and S. ox//colpos, Emmr., var. caucnsica, n.sp. 



In the bed of this rivulet, which flows into the Sokhra, there also 

 occurs a dark-grey, nearly black, ai'enaceous slate, very micaceous, 

 crowded with valves of Konincldna Telleri, Bittn., and also containing 

 well-preserved shells of Pelecypods {PJmnodesmia sp. and Niiciila 

 cf. strigilata, Goldf.). 



Even a cursory examination of the above fauna shows that this 

 formation, must belong to the Upper Trias, for some of the forms in 

 the foregoing list have been described by Suess and Zugmayer as 

 typical of the Kossen and Starhemberg Beds, e.g., T.pi/riformis, Suess, 

 TV. norica, Suess, Spiriferina Suessi, Winkler, S. kossenensis, Zug., 

 Spirigera oxycolpos, Emmr., R. fissicostata, Suess, whilst others are 

 representative of the Dachsteinkalk, e.g., W. {A.) frontalis, Bittn., 

 TF. {A.) refexa, Bittn., R. Fuggeri, Bittn., thus indicating an 

 equivalence with the Bhsetic stage of the Alpine Trias. The fauna, 

 which contains new forms peculiar to the Caucasus, also comprises 

 some characteristic Anatolian forms, described by Bittner in Mysia, 

 e.g., T. turcica, Spirigera Manzavinii, R. anatolica, R. levantina, 

 corresponding to the Eha3tic stage of the Alps or only slightly older. 

 In addition to the Brachiopods particular attention may be drawn to 

 the numerous well-preserved bivalves (occurring in the same beds), 

 which A. A. Borisiak, after careful comparison with the original fossils 

 in the Geological Museum of the Academy, referred to P. ochotica, 

 var. densistriata, Teller. 



A few words still remain to be said concerning the dark-grey, 

 arenaceous slates, in which there were found abundant valves of 

 K. Telleri, Bittn. Since the slates underlie the limestones, and this 

 fossil, which occurs so abundantly, is typical of the Alpine Upper Trias, 

 we may reasonably conclude that the Northern Caucasus possesses 

 a nearly complete series of Upper Alpine Trias. 



To judge from some indications given by W. I. Worobiev, the 

 Upper Trias has probably a wide extension on the northern slope of 

 the Caucasus ; and a considerable area, which in the absence of 

 palseontological evidence has hitherto been attributed to other 

 formations, may eventually be found to belong to the Upper Trias. 



II. BiBLIOGKAPHY OP MEXICAN GeOLOGY. 



IN 1898 the Instituto Geologico de Mexico published as Bulletin 

 No. 10, under the title " Bibliographia Geologica y Minera de la 

 Eepublica Mexicana ", a list of books and papers on Mexican geology 

 and mining consisting of xii -f- 160 pages, each 13 X 9 inches and 

 containing 1,953 items, arranged alphabetically under authors' names, 

 with an index of localities and a subject-index, the references extending 

 to papers published from 1556 to the end of 1896. This most useful 

 work has now been continued in Bulletin No, 17 (dated 1908) under 

 the same title with the addition " completada hasta el aiio de 1904 ". 

 Bulletin No. 17 consists of xiv + 332 pages, 13 X 9 inches, and con- 

 tains 4,252 items, arranged, as before, alphabetically under authors' 



