266 



NA TURE 



{July 19, 1888 



NEW WORKS ON LEPIDOPTERA. 



South African Butterflies : a Monograph of the Extra- 

 Tropical Species. By Rowland Trimen, F.R.S., &c, 

 assisted by James Henry Bowker, F.Z.S. Vols. I. and 

 II. Royal Svo. (London: Triibner and Co., 1887.) 



Descriptions of New Indiaii Lepidopterous Insects from 

 the Collection of the late Mr. W. S. Atkinsonj M.A. 

 Part III. Heterocera (continued). By Frederick Moore, 

 F.L. S., &c. 4to. (Calcutta : Published by the Asiatic 

 Society of Bengal, 1888.) 



MORE than twenty-one years have elapsed since Mr. 

 Trimen finished the publication of his " Rhopalo- 

 cera Africae Australis." During the whole of this time he 

 has kept the subject of South African butterflies steadily 

 in view, and the number of additional species discovered in 

 South Africa is so large that he has chosen a new title for 

 his book rather than call it a second edition of the old one. 



Between 1866 and the present time the number 'of 

 species of butterflies known to inhabit South Africa has 

 swollen from C22 to 380, and instead of a small octavo 

 volume we have now before us two out of three royal 

 octavo volumes of goodly dimensions. This progress in 

 the study of a favourite group of insects in South Africa 

 probably represents a similar progress in the knowledge of 

 the butterflies of the world, for nearly everywhere it has 

 been increased by rapid strides. 



Mr. Trimen has had the advantage of living in the 

 country the butterflies of which he describes, and he has 

 been in close correspondence with numerous enthusiastic 

 helpers, foremost amongst whom is Colonel J. H. Bowker 

 whose name appears on the title-page as Mr. Trimen's 

 coadjutor. 



The earlier chapters of the work are devoted to general 

 subjects relating to insects and leading up to the special 

 subject in view. In all this portion Mr. Trimen has exer- 

 cised admirable judgment, giving the leading points in 

 concise but clear language. • The classification adopted 

 is that of Mr. H. W. Bates, which has now stood the test 

 of many years' practical working, hardly any important 

 alteration having been made in its main features since it 

 was published. Still, much remains to be done before 

 some of the great families, such as the Lycaenidae and 

 Hesperidas, and sub-families, such as Satyrinse and 

 Nymphalinas, can be reduced to order. 



As is well known, the front pair of legs in the imago 

 provides one of the most important characters for deter- 

 mining the families of butterflies. Their examination 

 affords a most interesting study. Owing to improved 

 methods of preparing these limbs, whereby their scaly 

 clothing is either destroyed or rendered invisible, they 

 can be conveniently arranged for microscopic examina- 

 tion. The full extent to which they are atrophied is 

 thus clearly revealed. The front legs of the males in the 

 members of some families have their tarsal joints either 

 more or less fused together or reduced to a single 

 atrophied joint ; but the variation in the -extent to which 

 this takes place is great. It sometimes also happens that 

 when a number of individuals are examined, one will 

 be found in which rudimentary spurs appear, and even 

 unsymmetrically and attached to one tarsus only and not 

 the other of the same insect. In some cases recently 

 examined, ma'es in the Erycinidas have been found with 



the front legs furnished with the full complement of joints 

 and with claws. The like occurs in the Lycasnidae both 

 in America and in South Africa. Such, cases, however, 

 are exceptional, and though they break down to some 

 extent the universal application of these characters to 

 the discrimination of families, discrepancies are only to 

 be expected, and the wonder is there are so few of them. 

 Mr. Trimen appears to have studied this part of his 

 subject with care, but a closer examination than is usually 

 made will repay the labour of arranging the preparations. 

 Though the variation in the relative lengths of the femur, 

 tibia, and tarsus have been compared, the coxa has 

 seldom been taken into consideration. Yet it, too, 

 furnishes useful points for distinguishing forms, and in 

 the case of the Erycinidae the prolongation of this joint in 

 the male front leg beyond its junction with the trochanter 

 is diagnostic of the family. Mr. Trimen has not made 

 any use in his classification of the varied structures pre- 

 sented by the secondary sexual characters of the terminal 

 segments of the body ; but there can be little doubt that, 

 as improved methods of preparation are discovered, these 

 characters will be found very useful in determining the 

 relationship of species if not of genera. 



The limits of the fauna treated of, as the title of the 

 book states, extend from the Tropic of Capricorn south- 

 wards to the Cape of Good Hope. This district forms a 

 sub-region of the great African or Ethiopian region. Its 

 distinguishing characteristics are mainly negative, only 

 six out of the sixty-nine genera not being found elsewhere, 

 though 195 out of 380 of the species are peculiar. Whether 

 the northern limit of this section of the African fauna 

 really lies along the tropic remains to be seen, as our 

 knowledge of the butterfly fauna north of this line is very 

 meagre : of the interior we know nothing, and of the 

 coasts not much. Regarding the internal distribution of 

 the species, it would appear that the western and central 

 portions, as well as that in the neighbourhood of the 

 Cape, are poor in species. During a residence of over 

 twenty-five years, Mr. Trimen has succeeded in captur- 

 ing only forty-seven species within a radius of twelve 

 miles from Cape Town. In the eastern districts the 

 fauna is richer : Natal produces 206 species, and in the 

 neighbourhood of Delagoa Bay many additional species 

 occur. Each species is very fully described in this work, 

 and many useful notes are added whereby the allied forms 

 may be discriminated. Their history and range are also 

 given with great precision. The larvae and pupae of many 

 species are described, and this feature is a very acceptable 

 addition, as most works on exotic Lepidoptera are silent 

 on the subject. 



The portion of the introduction that will be read with 

 the greatest interest is that which relates to protection, 

 resemblances, mimicry, &c. (pp. 32-40). A concise 

 summary of the best .work on this subject is given ; and 

 the instances furnished by the African butterfly fauna are 

 described more in detail. Some years ago Mr. Trimen 

 brought forward some very interesting cases of mimetic 

 resemblances in butterflies, the most important being 

 that in which Papilio merope is involved. He was able 

 to prove that, wherever it is found, the females of this 

 species take the pattern of a Danais, and though the 

 males hardly vary over a very wide area, the female 

 varies with the Danais in each district except in 



