56: 



NA TURE 



[April 16, 1903 



sativus, and a number of others which might have been 

 eliminated as certainly introduced, and placed in a 

 separate list. As it is, without considerable labour, 

 one can only distinguish two elements, namely, the 

 endemic and the non-endemic, the latter comprising 

 both indigenous and certainly introduced species. It 

 is further complicated bv the fact that " undetermined 

 pei ius," " varieties," and " forms " are all tabulated 

 equally, and the percentages of the constituents of the 

 flora are calculated from mixed totals. 



For instance, the percentage of endemic species of 

 flowering plants is obtained from a total which includes 

 fifty " undetermined species," some of which, one 

 would suppose, are also endemic. On the other hand, 

 fifteen " varieties " and nineteen " forms " are in- 

 cluded in the calculation, by which the endemic element 

 is made out to be 44/4 per cent. This Dr. Robinson 

 designates an " extraordinary endemic element "; but, 

 as compared with some other islands and continental 

 areas, it is low. In the Hawaiian Islands it has been 

 placed at 81-4, in Juan Fernandez at 68-6, in St. 

 Helena at 61*3, in West Australia at 85, and in Central 

 America, including Mexico, at 70 per cent. This is the 

 specific endemic element. According to the now 

 generally accepted generic limits, there is almost no 

 generic peculiarity in the flora of the Galapagos. 

 Scalesia (Compositae), which is as well defined as many 

 other genera of this order, is confined to the archi- 

 pelago, where it is represented bv seventeen described 

 species, most of them inhabiting only one island. This 

 peculiarity; specially characteristic of the Galapagos 

 flora, is shared by several other leading genera, 

 amongst them Castela, Euphorbia, Croton, Acalypha, 

 Opuntia and Borreria. On the other hand, there are 

 some species peculiar to the archipelago but icpresented 

 in nearly all the islands. Telanthera echinocephala 

 (Amarantaceae), Oxalis Cornelli, Maytenus obovata 

 (Celastraceae), and Cordia lutca (Boratjinaceae) are con- 

 spicuous examples. 



But I must not attempt to summarise the whole of 

 Dr. Robinson's work. Briefly, he enumerates 500 

 named species of vascular plants, of which fifty-two 

 air ferns, only three of which are confined to the 

 islands. The 205 endemic species of vascular plants 

 include members of thirty-nine natural orders. The 

 orders most numerously represented bv endemic species 

 are Compositae, 39 ; Amarantacea?, 29 ; Euphorbi- 

 aceae, 25, besides 7 endemic varieties and 7 endemic 

 forms; Rubiacea?, 16; Gramineae, 13; and Boragin- 

 acese, 14, giving a total of 136, or two-thirds of the 

 whole, contributed by six orders. Against this there arc 

 seventeen other orders, limited to one endemic species 

 each. But the Cactaceae, the species of which are still 

 bully defined, are much more prominent and generally 

 dispersed than some of those much more numerous in 

 species. Members of the Cactaceae are recorded from 

 all of the islands except Gardner, but including the 

 small and remote Tower, YVenman, and Culpepper 

 Islands. The Leguminosa?, counting only six endemic 

 species, are also very prominent in the arboreous 

 'lenient, from the presence of the genera Acacia, 

 Cassia, Mimosa and Parkinsonia. Astragalus Edmon- 

 stonei is a noteworthy outlier of this genus, not found 

 by any recent collector. The presence of four species 

 "I the Loranthacea? is another interesting fact. 



The affinities of the flora of the Galapagos Islands 

 an' wholly American, for the very few exceptional 

 Species may be accidental introductions. In composi- 

 tion it differs from that of the smaller flora of Juan 

 Fernandez in having almost no generic endemic 

 i-lement, and in the specific endemic element being 

 furnished by relatively numerous natural orders. From 

 the flora of the Hawaiian Islands it also differs in being 

 much less highly specialised. There are no tree-ferns, 



NO. T746, VOL. 67] 



no gymnosperms, and, with the exception of grasses 

 and sedges, of which there are 52 and 23 species re- 

 spectively, monocotyledons are very poorly represented. 

 There is one orchid, Epidendrum spicatum, one brome- 

 liad, Tillandsia insularis, and Commelina nudiflora, 

 a very widely dispersed weed in warm regions, and 

 Hypoxis decumbens complete the petaloid series. The 

 aquatic genera Potamogeton, Ruppia, Naias, and 

 Lemna rest on single records of American collectors. 



Dr. Robinson concludes his essay with an examin- 

 ation of the " botanical evidence regarding the origin 

 of the Galapagos Islands." After a brief examination 

 of the evidence in favour of the opposed theories of 

 submergence and emergence, he says : — " During a re- 

 examination of the whole vascular flora of the islands, 

 I have sought further light upon this question, and 

 now find the peculiar distribution of the plants less 

 difficult to account for on the emergence theory than 

 it seemed when the Baur plants were studied some 

 years ago." I should like to discuss this " new light " 

 briefly in a separate communication, and will merely 

 remark here that all the proved means of dispersal of 

 the seeds of plants to long distances are insufficient, to 

 my mind, to account for certain insular floras generally 

 regarded as derived rather than as residues. 



W. BOTTING HEMSLEY. 



A NEW NATURAL HISTORY. 1 



THE increased interest in zoology certainly existing 

 at the present time is one of the causes which 

 has induced Prof. Davis to attempt a natural history 

 written on lines totally different from those usually 

 followed in works of this kind. In place of treating 

 the various animal groups in more or less full detail 

 according to their presumed relationship to one another, 

 it is proposed to consider them in relation to their 

 environment, and to lay special stress on the inter- 

 dependence of animals and plants, and the bearing 

 upon life of chemical and physical conditions. Such 

 a mode of treatment undoubtedly has great possibilities 

 before it, and is one which should do good by drawing 

 attention to our lack of knowledge as to the reason 

 of many of the structural peculiarities of animals. It 

 is, indeed, one of the reproaches that may be legiti- 

 mately brought against our present methods of zoo- 

 logical studv that we attach far too much importance 

 to describing and recording minute differences between 

 closely allied animals to the utter neglect of the study 

 of their life-history. Whether the author will be 

 successful in this mode of treatment we cannot at pre- 

 sent even conjecture, for the two sections of the work 

 now before us are devoted to a brief systematic survey 

 of the leading groups of the animal kingdom, which 

 must form a necessary introduction to its proper sub- 

 ject. These two sections may, indeed, be regarded as 

 a kind of " index-museum " to the rest of the work. 

 They are important as serving to show that from no 

 point of view can systematic zoology be neglected, and 

 also that the issue of a work like the present in no wise 

 renders the older type of natural history superfluous. 

 There is ample room for both, and neither poaches on 

 the preserves of its fellow. 



As a whole, the author's treatment of the systematic 

 part of his subject may be regarded as fairly successful, 

 and the volume before us is rendered highly attractive 

 to the general reader by the beauty of its coloured 

 plates and other illustrations. Where all are excellent 

 it is difficult to select any for special commendation. 



1 " The Natural History of Animals ; the Animal Life of the World in its 

 various Aspects and Relations." By J. R. A. Davis. Half-vols. i. and 

 ii. Pp. xxxii-f-429 ; illustrated. (London: Gresh tin Publi-hing Co., 19^3.) 



