Nov. 4, 1880] 



NATURE 



The second part of M. Wurtz's book, dealing with 

 Valency, is not, in our opinion, of equal value with the 

 first. 



After reading these chapters one finds it hard to find a 

 reason for introducing into science the conception of 

 valency, so variable and shifting is this property of atoms 

 made to appear. 



On p. 229 it is stated that chlorine is monovalent in 

 HCIO, pentavalcnt in HClOo, and heptavalent in HCIO- 



Scarcely a hint is given of the many objections to ex- 

 tending considerations concerning valency, in any but a 

 most tentative manner, to non-gasifiable bodies. The 

 theory of molecular as distinct from atomic compounds is 

 dismissed ; all are regarded as atomic, and the valencies 

 of the atoms seem variable at pleasure. Where proof of 

 the valency of atoms is not forthcoming, assertion is used 

 in its place. 



The author's treatment of aftinity is not satisfactory. 

 " Affinity is the force of combination, chemical energy." 

 " Atoms attract each other, and this atomic attraction is 

 affinity." "Thus we know that while hydrogen is united 

 to chlorine with extreme energy, oxygen combines with 

 less force." Surely the translator is to blame for some of 

 these sentences. 



The theory of valency deserved a more rigorous and 

 exact treatment than M. Wurtz has given it. 



We leave the book, feeling that it is the production of 

 a brilliant author, not the work of a deep thinker. 



M. M. P. M. 



NEW ZEALAND MOLLUSCS 

 Manual of tJic New Zealand Mollusca. By Frederick 

 Wollaston Hutton, F.G.S. Published by command. 

 (Wellington, iSSo.) 



IN an interesting article which appeared in Nature, 

 vol. xxii. p. 461, entitled " The Ne\y Zealand Insti- 

 tute," attention was called to the publications of the 

 Institute and to the excellent work in science achieved by 

 the author of the manual above mentioned, and by many 

 other naturalists, as well by geologists, chemists, astrono- 

 mers, archreologists, physicists, and philosophers. When 

 the traditional New Zealander visits the ruins of the old 

 country, it is to be feared that he will lament our igno- 

 rance instead of expressing his admiration of our past 

 eminence. 



Prof Hutton seems to have contributed to the publi- 

 cations of the Institute a number of valuable papers on 

 " the various divisions of the fauna of New Zealand." 

 We are not quite sure that our knowledge of any one 

 department of the fauna would be so much advanced by 

 a multifarious zoologist as by a specialist who has de- 

 voted himself to the study of that department. The 

 division of labour is not less desirable in natural history 

 than in other equally extensive fields of work. The 

 material is so vast that a Linne, Buffon, or Cuvier would 

 be now rather an anachronism than a marvel. 



The present work is called " A Systematic and Descrip- 

 tive Catalogue of the Marine and Land Shells, and of 

 the soft MoUusks and Polyzoa of New Zealand and the 

 adjacent Islands." It belongs to the Colonial Museum 

 and Geological Survey Department, of which Dr. Hector, 

 the well-known geologist, is the director. Its scope is 



most useful ; and, as the preface by Dr. Hector very 

 properly states, " an accurate knowledge of the affinities 

 and distribution of the recent shells of New Zealand is 

 a very necessary element in the geological survey of the 

 country, as it must form the basis of our Tertiary geology, 

 upon the correct deciphering of which many questions of 

 the highest interest depend." And he adds, " Shells 

 afford the most reliable data for palaeontologists ; but 

 before the extinct shell-fauna can be utiUsed, the recent 

 shells of the area must be thoroughly determined." This 

 is quite true. We are disposed, however, to carry the 

 process a step further. It is not enough to determine or 

 make out the recent shells, but they must be critically 

 compared with their fossil analogues. For want of such 

 comparison the late Prof. Nyst, M. Vandenbroeck, and 

 other Belgian palasontologists have unfortunately caused 

 some confusion by a wrong identification of recent or 

 living species with Tertiary species. 



The "Manual" contains 237 page?. There are no 

 plates or illustrations. It appears to comprise all that is 

 known of the subject, and to have been conscientiously 

 and on the whole carefully written. But, like all other 

 books, it is not faultless. In the Bibliography " Linneus " 

 is the name given as the author of the 12th edition of the 

 " Systema Nature." It ought to be "Linne," according 

 to the title-page and dedication. "Gastropoda" is 

 now the usual, as well as correct, spelling of the class, 

 not " Gasteropoda." The shell of the family Patellida: 

 is not a simple cone, but is spiral in the young. The 

 Bullidu: are not all eyeless. The sub-order " Lucinacea" 

 is described as having the gills, " one on each side " ; but 

 in one of the families of this sub-order there are " two 

 gills on each side." The family " Radnlida" is stated to 

 have the foot " not byssiferous " ; LimaJiians with its foot 

 spins a byssus and makes its curious nest. In the " Arti- 

 ficial Key to the Marine Shells" the remarkable class 

 Solenoconchia (or as Prof. Hutton in another place prefers 

 to call it, "Scaphopoda") is omitted. The shell in " Capii- 

 lida" is described as "not spiral." These and other 

 less important errors can be corrected in a future edition. 

 We regret, but are not surprised, to see the remark that 

 " not much dependence can be placed on the localities in 

 Mr. Cuming's collection," which was purchased for the 

 British Museum at a large price. This is the case with 

 all dealers, and it sadly disturbs our ideas of geographical 

 distribution. We are inclined to question even such 

 species as Ostrea edttlis, Mytilns edulis and Liicina 

 {Loripcs) divaricata as indigenous to New Zealand. 

 These are included in a list of sixty-four species believed 

 by the author to be the only New Zealand species of 

 which there is evidence that they are found anywhere 

 else, although he admits that the identification has 

 in most cases been made solely by descriptions and 

 figures. The same remark applies to Cypraa curopaa, 

 " Philippia lutea" = Solarium hybridum, Littorina cant- 

 Icscens = ueriioides, and Crcpidula unguiformis. But, per 

 contra, the Saxicava australis of Lamarck is scarcely a 

 variety of S. rugosa, Linnd The diagnosis of the soft parts, 

 or " animal," of Vitrina and Succinca, viz., " too large to 

 enter the shell," does not suit the European species of 

 those genera. In the family Assiminiidce the eyes are 

 placed not " on the middle of the tentacles," but on their 

 tips. " Odostomia lactea'' is not the Linnean species of 



