556 



NA TURE 



lApril 15, 1886 



in the process. Shearing does not necessarily involve 

 flattening, though in a large number of cases the two 

 would doubtless go together. For this reason tt is not 

 correct to speak of cleavage as due to " shearing " 

 (p. 255) : shearing alone will not produce all the pheno- 

 mena of cleavage ; there must be flattening of the 

 particles as well. Under the head of "'Joints," instead of 

 vaguely stating that some joints may be due to compres- 

 sion or torsion, would it not have been better to introduce 

 a few lines about Daubr^e's experiments, which almost 

 bring a conviction that the majority of joints in sub- 

 aqueous rocks are due to torsional strain ? 



In Part III., to which some of the above criticisms 

 apply, we have a clear account of the way in which the 

 crust of the earth is built up out of the materials de- 

 scribed in Part II. Then follows Part IV., " The Geo- 

 logical Record of the History of the Earth." This must 

 necessarily be presented in an abridged form, and if any 

 fault is to be found with the way in which the subject is 

 handled, it might perhaps be said that an atteurpt has been 

 made to be rather too encyclopffidic. Graphic pictures, 

 suchasthe author can so well pen, of the physical geography 

 of our own countay, and, where necessary, of the adjoining 

 parts of Europe, during the different geological periods, 

 would perhaps have been more acceptable and instructive 

 to most of those who will read this book than palaeonto- 

 logical details and accounts of the range of formations 

 through other lands. For instance, the sketch of the 

 physical geography of Europe during the Triassic period 

 on p. 380, strikes us as singularly happy, and we should 

 like to have seen more of the same kind of thing in the 

 book. We all know how the pigeon-hole geologist deals 

 with this question ; how he produces his parallel ruler 

 and divides his sheet of paper nearly into squares ; how 

 he puts the names of countries into the squares on the 

 top line and the names of formations into the squares 

 down one side, and then proceeds to fill in his puzzle. 

 Under the column " England," line " Muschelkalk,' he 

 inserts " Wanting." Ha ! says he, a whole formation 

 missing ! great unrepresented interval ! there must be a 

 corresponding unconformity. Primed with this idea he now 

 takes to the field, finds that the evenly-bedded New Red 

 Marl does lie irregularly on the false-bedded sand-banks 

 of the New Red Sandstone, and is overjoyed to see the 

 unconformity which his chess-board told him must be 

 there. Had he used, in trying to realise the meaning of 

 the geological facts, half the ingenuity he showed in dis- 

 torting them in order to fit them on to his Procrus- 

 tean bed, he would have seen that what is called the 

 Muschelkalk is not the only marine intercalation in the 

 Trias of Central Europe, but that minor muschelkalks 

 occur both in the Keuper and Bunter ; that each of these 

 marks an advance of the Triassic sea over the district 

 where they are found ; and that the reason why neither 

 the great nor the little muschelkalks are found in 

 England is that the sea did not succeed in pushing its 

 way as far west as our country during any of its incur- 

 sions. But there is no pigeon-holing in the book before 

 us, and where the author has tried to bring before us a 

 picture of the physical geography of bygone time, he has 

 been so successful that we wish he had given us more of 

 them. 



A. H. G. 



OSCAR SCHMIDT'S ''MAMMALIA" 

 T/ie liTamiiia/i'a in their Relation to PriiniTval Times. 

 By Oscar Schmidt. International .Scientific Series. 

 (London: Kegan Paul, Trench, and Co., 1885). 



'X' HE numerous and important discoveries that have been 

 made in the last few years in extinct forms of mam- 

 malian life, and the light that hasbeen thus thrown upon the 

 relations of the surviving species, render a popular sum- 

 mary of our present knowledge of the class a very desir- 

 able undertaking. Moreover any work which, by showing 

 the intimate relation of the present with the past, aids in 

 breaking down the custom, which has descended to us 

 from an antiquated condition of scientific culture, of 

 treating separately of the existing and the extinct forms 

 of life, of speaking of zoology and palaeontology as if they 

 were distinct subjects, must be welcomed by the philo- 

 sophical naturalist. 



In undertaking such a work the late Prof Oscar 

 Schmidt, of Strasburg (whose death we regret to say has 

 been recently announced), acknowledges that he was 

 departing from the specialty in which he had so highly 

 distinguished himself, and was deriving his materials 

 entirely from the researches of others. But the subject 

 evidently had strong attractions for him, and he has most 

 industriously and impartially compiled from the best 

 authorities a work which, if it had been written in any 

 one of the languages of the series of which it forms a 

 part would have well served the purpose intended. The 

 attempt, however, to give it a truly " international " 

 character, by bringing it out in a combination of two 

 languages, is unfortunately anything but successful. 

 Words are continually occurring, which, though perhaps 

 literal translations of German pseudo-vernacular expres- 

 sions of modern manufacture, can convey no meaning 

 to the English reader, whatever assistance he may get 

 from the dictionary, as for instance, " spoon-dog " (for 

 the African large-eared fox, Otocyon lalandii), " fingered- 

 animal " (for Chiromys), " forked-animals " (for the 

 Monotremata), " dog-fish " (for seal) ; and such expres- 

 sions as "mid-jawbone," "root of the hand," "middle 

 hand," "skiff-bone," and "spoke" are far less intelligible 

 to the student of ordinary education than their generally- 

 accepted scientific equivalents " premaxilla," " carpus," 

 "metacarpus," "navicular," and "radius." Misprints 

 and inaccuracies abound everywhere, such as the habitat 

 of the small species of hippopotamus being transferred 

 from Liberia to Siberia, the reference to " African arma- 

 dilloes" and to Prof Huxley's discovery of fibrous epipubic 

 structures " in several hundred different species of dogs " ! 

 As a specimen of style we may quote the following 

 sentence : — " When it is said that the Marsupials 

 'vicariate' in Australia for the other groups distributed 

 on the other continents, this expression denotes nothing 

 but the bare fact, nothing but the mere statement, that in 

 America we do not meet with the camel but with the 

 llama, which in a few main characteristics shows some 

 affinity with it" (p. 13). With the general argument 

 against the idea that the expression " vicarious," or, as 

 English authors generally say, " representative," species 

 offers no explanation of the facts of distribution we en- 

 tirely agree, and we can even see what was floating 

 through the author's mind when this extraordinary sen- 



