532 



NA TURE 



[April 9, 1896 



the account of the flora of that period, by the description 

 of the Cycads and ConifercC. The complete absence of 

 Angiosperms from the Wealden is disappointing and 

 surprising, for it was unquestionably at that period 

 that the higher flowering plants were evolved. Both 

 in the Potomac beds of America and in rocks of the 

 same age in Portugal, there are remains of monocotyle- 

 dons and dicotyledons. Angiosperms have been also 

 recorded from the Wealden ; but Mr. Seward, after a 

 careful consideration of the evidence, dismisses it as in- 

 valid. Mr. Seward's catalogue contains a full descrip- 

 tion of all the known plants from the Wealden series, 

 and he is to be congratulated on having expanded his 

 catalogue into a complete monograph of the whole 

 flora, which numbers seventy-six species. The present 

 volume contains the description of twenty-four Cycads 

 and seventeen Conifers, of each of which as full an 

 anatomical account is given as the material allowed ; the 

 genera are discussed in detail, and important additions 

 made to the knowledge of their structure and affinities, 

 as in the case of Otozamites and Bennettites. Mr. Seward 

 gives a full bibliography. He discusses the relations of 

 the British flora to their foreign representatives, their 

 geological position, and their evidence as to the climatic 

 conditions under which they lived. His conclusions on 

 these subjects are of great interest. He says the climate 

 was apparently tropical, and that the temperature must 

 have been considerably warmer than that which rules in 

 the Wealden district at the present day (p. 239). It is 

 barely necessary to point out, that geologists have always 

 included the Wealden deposits in the Cretaceous ; but 

 Mr. Seward tells us that "the evidence of palasobotany 

 certainly favours the inclusion of the Wealden rocks in 

 the Jurassic series." This conclusion is in accord with 

 that of other lines of pala^ontological evidence, and it 

 may be hoped that Mr. Seward's pronouncement will 

 hasten the inevitable dismemberment of the Wealden 

 series into two groups, the equivalents respectively of the 

 Neocomian and Portlandian series. 



If we miss in Mr. Smith Woodward's catalogue the 

 geological conclusions which render Mr. Seward's so 

 interesting, it is certainly superior to it in one respect ; 

 viz. the conciseness, and precision of the diagnosis of 

 orders, families, genera, and species. In such catalogues 

 we too oftea only have the synonymy and indefinite 

 descriptions of specimens, instead of definite, accurate 

 diagnoses. In this respect Mr Smith Woodward's work 

 is a model. The arrangement is strictly zoological, and 

 thus the volume will be mainly of interest to students of 

 icthyology. The main task of the volume is to trace 

 the gradual evolution in the Actinopterygi from the lower 

 Chondoestrean type to that of fish which approximated to 

 the Teleostei. Mr. Smith Woodward describes the suc- 

 cessive modifications of the Mesozoic fish fauna, whereby 

 this evolution has been effected. His classification 

 therefore represents, not an a priori scheme as to the 

 probable life-history of the fauna, but an actual life- 

 history as revealed by the records of the rocks. In 

 groups of animals where the fossil remains are sufficiently 

 abundant to enable this to be done, this is the ideal 

 system of classification. Mr. Smith Woodward intro- 

 duces such revolutionary changes into the families and 

 orders, that he has been obliged to abandon the attempt 

 NO. 1380, VOL. 53] 



to show the relations of the divisions he accepts, to 

 those of his predecessors, by synonymic tables. The 

 author is greatly to be congratulated on his treatment of 

 such genera as Acipenser, A?nia, and Lepidosteus. As 

 members of these genera still survive, they can be 

 dissected and their anatomy studied in detail. Hence it 

 has been the custom to take them as the types of the 

 Chondrostei, Protospondyli, and ^theospondyli re- 

 spectively. But as these living genera are only de- 

 generate, or at least remarkably specialised forms, they 

 give a very misleading idea of the typical members of 

 the Actinopterygi. Mr. Smith Woodward, therefore 

 reduces them to their proper position, as aberrant off- 

 shoots from the main stem. This volume is a bulky one, 

 and it is impossible in a brief abstract to give any idea of 

 the amount of new information it contains. The 

 anatomical structure of each genus is carefully worked 

 out, so that the systematic conclusions are based on 

 morphological characters. Many of the more important 

 genera are also illustrated by restorations, while the 

 series of diagrams of the cranial osteology are most 

 instructive. 



Reference must also be made to the thirty-eight clear 

 and artistic plates, which have been drawn by Miss 

 G. M. Woodward for the two catalogues. 



OUR BOOK SHELF. 



The Hymenoptera Aculeata of the British Islands. A 

 Descriptive Account of the Families., Genera, and 

 Species indigenous to Great Britain and Ireland., 

 with Notes as to habits, localities, habitats, Ss^c. By 

 Edward Saunders, F.L.S. 8vo. Pp.viii-f 391, (London: 

 Reeve and Co., 1896.) 

 A GREAT number of books are published at presen 

 relating to the more popular orders of insects, especially 

 British butterflies and moths. Some entomologists,, 

 however, devote their attention to the more varied fauna 

 of warmer climates, and publish valuable monographs 

 on the insects of Central America, Asia, or Africa. We 

 are glad to find that others make the less fashionable, if 

 equally interesting, orders of British insects their study : 

 and although there are still many groups, and even 

 whole orders of British insects of which we do not at 

 present possess any trustworthy monograph, their number 

 is lessening year by year. Mr. Saunders deserves special 

 praise for his labours in this direction. After publishing 

 one or two useful works on foreign insects, he turned his 

 attention exclusively to British entomology. He has 

 given us a work on British Hemiptera, which is to be 

 followed by one on British Homoptera j while the book 

 before us relates to the British Nyjnenoptera Aculeata., 

 the section of the vast order Hymenoptera which includes 

 the bees, wasps, and ants, in which the ovipositor is 

 usually modified into a sting in the females, though in 

 some families, as in the first family of ants, the typical 

 FormicidcE, the insects do not sting, though some of 

 them bite very severely. 



It is not the first time that Mr. Saunders has dealt with 

 the Hymenoptera. Synopses of the British Aculeata were 

 published in the Transactions of the Entomological 

 Society of London some years ago, in addition to im- 

 portant papers on structure ; and the former, enlarged and 

 brought down to date, have formed the basis of the pre- 

 sent work. He regards the Hymenoptera as entitled, 

 both by their intelligence and structure, to stand at the 

 head of the insect world ; and they reach their highest 

 development in the Aculeata, which, at present, number 

 374 British species. Full characters of species and genera 

 are given, including elaborate tables of species. Three 



