Geology, 405 



di Torino. 150 pp. 8vo. Florence, 1889. — Dr. Ricoiardi here 

 its of the various volcanic rocks of Italy, gives their chemical 

 composition, distribution, the results of their decomposition and 

 the character of the soils they afford. He discusses the effects of 

 atmospheric agents in producing decomposition and among them 

 those of vegetation, the Lichens, Diatoms, and Bacteria. One of 

 the most characteristic lichens of volcanic regions, the JStereocaulon 

 Vesuvianum, afforded in two analyses, one of them of specimens 

 from the Leucitic lava of Vesuvius : 



SiO a 



A1 2 8 



Fe 2 O s 



FeO MgO 



CaO 



Na 2 



K 2 



P.O. 



1. 46-40 



11-13 



- - - • 



20-40 2-51 



14-78 



_ _ _ _ 



2-28 



tr. = 9749 



2. 4(3-41 



19-67 



6-88 



4-17 5-2S 



10-53 



2-02 



4-09 



= 9900 



The amount of ash is stated to be 11*16 p. c. of the dried lichen. 

 Special soils of various localities are next described in detail and 

 their origin considered. 



11. Fauna der Gaskohle, etc., Der Permformation Bohmens. 

 Band ii, Heft 4. Prague, 1889. Dr. Ant. Fritsch. — Dr. Fritsch's 

 work on the Vertebrate fossils of the Permian or Upper Carbo- 

 niferous of Bohemia has long been favorably known to geologists. 

 The earlier parts, on the Batrachians of the order Stegocephala 

 and its allies, have added very much to our knowledge of this 

 group, and the later parts on the fishes prove equally interesting, 

 as illustrating some of these in a much more perfect manner than 

 has hitherto been possible. Vol. ii, pt. 3, published in 1848, 

 describes the Dipnoi, and in part 4, just issued, the author is 

 enabled to restore a species of Ctenodus (C. tardus) in such a 

 manner as to bring out very distinctly its remarkable resemblance 

 to the modern Barramunda of Australia (Ceratodus). It is most 

 interesting to see these fish, hitherto mostly known by detached 

 teeth, thus restored and compared in their details with their more 

 modern relatives, as well as with those of the Devonian and Silu- 

 rian. The figures also throw much light on curious bones and 

 scales found with the Ctenodus teeth, with which collectors in the 

 Carboniferous are familiar. 



Part 4 is devoted principally to another group, the sharks of 

 the genus Orthacanthus Agassiz, a genus established by the 

 great worker in Paleozoic fishes for a group of straight, striated 

 spines often with denticles near their points, but which it now 

 appears is synonymous with the genus Diplodus of the same 

 author founded on the teeth. Egerton, Newberry, Cope and 

 others have remarked on the probable identity of the two genera, 

 from the occurrence of Orthacanthus spines and Diplodus teeth 

 in the same beds. The writer, before knowing anything of the 

 views of these authors, stated in 1869 a similar conclusion from 

 the frequent association of the spines and teeth on the shales of 

 the Pictou coal field in Nova Scotia.* 



Fritsch now presents us with illustrations of specimens in 

 which the cartilaginous skull and jaws are in great part preserved, 



* Second edition of Acadian Geology, p. 211. 



