Reviezv of Recent Geological Literature. 67 
that previously made known, come from the same yellow-brown, fine- 
grained micaceous sandstones. 
The Lower Silurian fauna occurs in a sandstone in the province of 
Salta, in northwest Argentine, but in limestone and dolomite in the 
middle of that country, in the province of San Juan. The species de- 
scribed are: Megalaspis sp., Be/terop/ion sp., Didymograptus sp., 
Illenus argeittinus, Maclurea avellanida;, Leptcrna sericiaSow., Orthis 
ccElligramina Dalm (?). 
The species here figured with others previously described are consid- 
ered to indicate a considerable range of Lower Silurian beds, including 
the orthoceratite limestone at the base and other beds toward the top 
of the system. 
The Devonian fauna of middle Argentina is contained in clay slate 
(lower part of the terrane) and slate and graywacke (upper part). 
The following species are described: 
Cryphcens, Phacops cf. rana Green, Hoiitalonotus sp., Orthoceras, 
sp., Naticopsis ? sp., Bellerophoit ?,-p.,Bet/erop/ioii aff. tnurchisoni d" 
Orb., Comdara qtiichua A. Ulrich, Tentaciclites sp., Leptodoi/ius s^. 
Pholadella radiata Hall, Allorisnia sp., Tropidoleptus fascifer n. sp., 
Liorhynchiis bodcnbcnderi n. sp., Liorhynchics ? brackebuschi, n. sp. 
Meristella ? sp., Leptocoelia acntiplicafa Conr., Vitnlina pusticlosa Conr. 
Spirifer antarcticiis Morr. and Sharpe, Orthothetes sp., Orthothetes 
cf. arctostriatus Hall, Chonetes falklandica Morr. and Sharpe, Chone- 
tes fuertensis, n. sp., Chonostrophia, Lingula {Dignonia) subalveata 
n, sp., Orbiculoidea cf. humilis Hall. 
The fossils are considered to indicate the lov^er and middle parts of 
the Devonian system. 
In this region the Silurian (Upper) is wanting, as the Devonian beds 
rest directly upon the Lower Silurian limestone, and consist of strata 
of the kind above described, having a thickness of several hundred to 
two thousand metres. Three fossil iferous horizons have been recognized 
in this mass of sediment. 
The Devonian fossils of lake Titicaca were found in loose pieces 
scattered- over the surface of an island-like elevation in the lake and 
plain. The fossils found were Leptoccelia flabellites Con., a Retzia 
and a Homalonotus. G. f. 
Petrology for Students. An Introduction to the study of roclcs un- 
der the microscope. By Alfred Harker. (2nd edition, revised, viii 
and 334 pp.; University Press, Cambridge, 1897, price, 7s. 6d.) 
The second edition of this text book, revised throughout and in 
part rewritten, does not differ materially in manner of treatment from 
the well known first edition, which was noted in the Geologist, 
vol. xvii, p. 2)'^'], and thus does not require an extended review. The 
divisions of igneous rocks — plutonic, hypabyssal and volcanic — are 
retained, and the amount of detail as regards reference to special types 
and descriptions is increased, especially for American localities. The 
