28 



NA TURE 



{May 



ing epoch, especially as the intervening links are, in ali 

 probability, absent." 



Mr. Blake selects certain species of Crtliocerata which 

 may have been produced by descent ; at the least it is 

 only supposition, and he states that there is no proof that 

 they arc actually so connected, but to the general theory 

 of evolution — which merely states that every form of life 

 has been developed from a preceding one nearly allied to 

 it — the present study affords no contradiction or difficulty 

 but affords aid — which if not so great as could be desired, 

 is yet as much as could be expected. In the present 

 ■study of the Palaeozoic Cephalopoda we have a fair repre- 

 sentative of a successive fauna of the same class, and 

 the species are grouped round a series of central types ; 

 and so long as the surrounding circumstances remain 

 constant and the same, the process of evolution by in- 

 definite variation and survival of the fittest should either 

 be uniform, and leave relics having no special grouping, 

 or it should cease when the best adaptation to the sur- 

 rounding circumstances or conditions had been acquired. 

 These views are expressed and carefully argued by Prof. 

 Blake, in the concluding pages of his work. " The great 

 defect," writes Mr. Blake, " of the theory of natural selec- 

 tion is that it leaves the original variation, which is the 

 basis of the whole to chance ; chance variations are not 

 likely to lead to any law." " The part which it has 

 effectually performed is to show how variations of the 

 individual may produce permanent changes in the species, 

 and thus break down the idea of the fixity and independ- 

 ence of the latter." "We are, perhaps," says the author 

 " as yet too dazzled by the brilliancy of the theory to per- 

 ceive its inadequacy as a complete account of life or to 

 place it as one link only in the chain of explanations." 



The " General Observations " of Prof. Blake on pp. 

 237-44 are a fitting termination to the laborious part 

 undertaken by him in describing the 145 Silurian species. 

 The work has been most carefully and honestly done, and 

 nowfor thefirst timewe possess a complete monograph upon 

 the Tetrabranchiate Cephalopoda of the oldest Palaeozoic 

 rocks ; no less than 31 quarto plates illustrate the species, 

 and all are drawn life-size. Mr. Blake has examined 

 2000 well-characterised specimens, and has visited all the 

 museums and private collections in Britain likely to con- 

 tain materials for his work, and as he remarks, the work 

 includes a description of every known specimen so far as 

 it presents any available characters. 



The fragmentary state of nine-tenths of the specimens 

 collected, demanded from the author the most careful 

 examination, whether by comparison or through descrip- 

 tion of specimens, and those who know the condition of 

 Silurian Cephalopoda as occurring in this country will 

 indeed appreciate the critical labour of Prof. Blake ; he 

 has rendered great service to palaeontology. The book 

 was the one want, as a completion to the works of 

 Murchison, McCoy, Salter, and Sowerby in Britain , a 

 companion to the grand monographs by Barrande upon 

 the Cephalopoda of the Silurian Rocks of Bohemia, also a 

 fitting accompaniment to the monograph by De Koninck 

 upon the same group for the Silurian and Carboniferous 

 Rocks of Belgium. No library devoted to natural science 

 should be without this first volume, and no student of 

 Palaeozoic species can do without it. No group of inverte- 

 brata are of such importance to the stratigraphical 



geologist as the Cephalopoda; in Britain alone the 

 Palaeozoic species number nearly 400, and in Bohemia 

 the Silurian Cephalopoda, as described by Barrande, 

 reach the great number of 1600, the Devonian species 

 500, and the Carboniferous species of Europe 350 species; 

 these totals will at least give some idea of the life and 

 distribution of this class of mollusca through time in 

 Europe, and as Prof. Blake's first volume only treats of 

 the Silurian of Britain, we wish him further success in his 

 continued work upon the British Devonian and Car- 

 boniferous species, the fossil forms in which require the 

 most minute, careful, and detailed study. R. E. 



OUR BOOK SHELF 

 Social History of the Races of Mankind. Fifth Division : 



Aramaans. By A. Featherman. (London : Triibner, 



1881.) 

 We do not like to discourage a student who has evidently 

 a zeal for knowledge, and must have given great labour to 

 compiling the comprehensive account of human society, 

 of which this volume is the first instalment published. 

 But we are bound to say he does not seem alive to the 

 differences of value among the travellers' books of which 

 he gives a list at the end of each section, and out of 

 which he has pieced together extracts describing Jews, 

 Arabs, Egyptians, &c. Thus some statement about the 

 Copts may be out of Lane's " Modern Egyptians," or it 

 maybe out of Miss Lot's "Nights in the Harem," and 

 the reader would rather like to know which is which. Mr. 

 Featherman writes in his preface : " The facts have been 

 selected with critical discernment, and no doubtful or in- 

 credible statements are admitted in the text, unless con- 

 troverted in a footnote." Then follows an introduction, 

 which begins : " The primaeval man did not spring from a 

 single stock, or from one ancestral type. He arose under 

 varying conditions, and at different geological periods. 

 The initiatory forces of nature which caused his primi- 

 tive development, existed in the same degree in all the 

 isothermal regions of the earth, and whenever the favour- 

 able circumstances were capable of producing and foster- 

 ing into maturity the human animal, there he appeared," 

 &c, &c. Putting preface and introduction together, it is 

 plain that the author's critical discernment does not 

 enable him to know a doubtful statement when he sees it, 

 even when it is of his own making. In fact he does not 

 quite know- where he is, or a casual look into his volume 

 would not show the ancient Egyptians classed among the 

 Aramaean or Semitic nations without mention of their 

 great physical difference from Jews and Arabs, nor would 

 there be found in the account of the Egyptian religion a 

 mention of Isis as being Ceres and Proserpine, mother 

 and daughter at once. The book deserves a place on the 

 library shelf, and will be useful to students, especially for 

 its descriptions of Druses, Talmud Jews, and other little- 

 known minor groups. It is doubtful if its reception by 

 the public will justify the series being continued ; but in 

 case it goes on, the materials ought to be more carefully 

 selected, and references given. 



Commercial Organic Analysis. By A. H.Allen. Vol. II. 



(London: Churchill, 18S2.) 

 The first volume of Mr. Allen's work treated of cyanogen 

 compounds, alcohol derivatives, phenols and acids ; in 

 this second part the very useful and practical character 

 of the work has been fully maintained in the description 

 of the properties, tests and assay of the hydrocarbons, 

 fixed oils, and fats, sugars, starch and its isomers, alka- 

 loids and organic bases, &c. The author has omitted, as 

 stated in his preface, all mention of dyes and colouring 

 matters, coal-gas, and animal products, on the ground 

 that their consideration would have inconveniently in- 



