TRANSACTrONS OF THE SECTIONS. 79 



On tJie Distribution of Mosses in Great Britain and Ireland as affecting the 

 Geography and Geological History of the present Flora. By John Shaw, 



Notes on the Structure of the Echinoidea regularia, with Special Reference 

 to their Classification. By C. Stewart. 



On the Traces of an Irish Lal-e DwelUmi , found by Captain L'Estrange, in 

 the County of Cavan . By W. Tennaut. 



On a Remarhable Mode of Gestation in an undescribed Species of Arius. 

 By Professor W. Turnee, M.B., F.R.S.E. 



In this paper a new species of Arius, from Ceylon, which the author named A. 

 Boakeii, atter the Rev. I3arcroft Boake, of Colombo, Ceylou, by whom it was first' 

 sent to this country, was described. This fish lays eggs about the size of small 

 bullets, which the male fish takes into his mouth and retains there until the young 

 are ready to leave the eg^. About twelve eggs come to intra-ovarian maturity at 

 one time, which is the number that the male can hold in his mouth. Although 

 Messrs. Wyman,Gunther, and Agassiz have described American fish which have the 

 same habit, this is the first specimen of a fish of the Old World in which this re- 

 mai-kable mode of incubating the ova has been obsened. The paper, with various 

 anatomical and zoological details, is printed in e.vtenso in the ' Journal of Anatomy 

 and Physiology,' November 1866. 



On Reversed Sexiud Characters in a Butterfly, and their Interpretation on the 

 Theory of Modifications and Adaptive Mimicry (^illustrated by specimens). 

 By A. R. Wallace. 

 The author exhibited a Malayan butterfly (Dtadema, n. sp.) the male of whicli 

 was of a dull brown colour, while the female was i-ichly glossed with metallic blue 

 — colours which in all the allied species are characteristic of the male sex. He 

 then showed that the female butterfly so closely resembled the very common Euplaa 

 midamus that it could not be distinguished from it on the wing. The Euplcece, and 

 the whole family Danaidre to which they belong, as well as the Heliconidte of 

 South America, are protected groups, and are the subjects of imitation by many 

 other butterflies and moths. The special protection the Danaidse possess was sup- 

 posed to be their very strong and peculiar odour, which rendered them distastenil 

 to insectivorous birds ; and the reason why the female only of the Diadema had 

 acquired protection by closely resembling the Euplcea was, because in all insects the 

 female is of more importance than the male, and it is necessary, in order to ensure 

 the continuance of the race, that her life should be preserved while she is engaged 

 in depositing her eggs. This was held to be a crucial instance of the truth of the 

 Darwinian hypothesis ; as what appeared at first sight a strange and unaccountable 

 anomaly, was shown to be under certain conditions the necessary consequence of 

 the " preservation of favourable variations in the struggle for life." 



The Poor Man's Garden. By N. B. Ward, F.R.S. 



On some points in the Structure of Limulus, Recent and Fossil. 

 By Heket Woodward, F.Z.S., F.G.S., &c. 



In this communication the author pointed out that although the classification 

 proposed by Professor M'Coy for Litnulii,", Belinurus, and Eioypferus in 1849 was 

 founded upon veiy imperfect data, yet subsequent researches tended to show that 

 a near relationship did exist betv\'een the Xiphosnra; and the Euryptcridce. 



Air. Woodward cited the published observations, descriptions, and figures of 

 species belonging to these two groups, by Professors Agassiz and Hall (in America), 

 Dr. Nieszkowski ( in Russia), Professor Huxley and Mr. J. W. Salter (in England), 

 and Mr. W. H. Eaily (in Ireland), and he likewise referred to his own investi- 

 gations in confirmation of his views. 



