

April 2-^, 1889] 



NATURE 



611 



.<2anic character, the rocks composing them being volcanic 

 conglomerates, breccias and tuffs, together with felsitic, 

 trachytic and basaltic lavas, the more acid types of which 

 show well-marked flow-structures. The vents from which 

 these lavas were erupted are situated chiefly in the large 

 island of Chusan ; another focus of emission is probably 

 represented by Changtau Island. 



One of the most noticeable features of the group is 

 presented by the vast stretches of land that have been 

 rescued from the sea. Many islands formerly isolated 

 have been united ; and broad plains of rich alluvial 

 ground have been reclaimed, are now highly culti- 

 vated, and support a dense population. This has been 

 chiefly brought about by the construction of strong em- 

 bankments and sea-walls from point to point across the 

 bays, after the latter had been allowed to become partly 

 silted up by the mud brought down from the Yangtsze 

 River and Hang-chow Bay. This difficult work testifies 

 to the marvellous energy and industry of the Chinese. 



Details are given of the geology of the following islands 

 of the Archipelago : — 



Video Island, the outermost of a long chain of 

 islands, extending in a west-south-west direction, has 

 a conical shape, with steep cliffs, and consists of a 

 pinkish quartz-trachyte, penetrated by numerous dykes 

 •of basalt. 



Tripod Island, an elongated island, about 600 feet 

 high, sloping moderately to the west, but descending on 

 the east almo t perpendicularly into the sea, is composed 

 -of a volcanic breccia, frequently penetrated by dykes of 

 basalt. 



Keusan Island, a high island of irregular elongated 

 ^hape, separated from Changtan Island by a narrow 

 •channel of ^-j fathom_s, with a good anchorage, presents, 

 at its north-eastern end (Radstock Point), a coarse vol- 

 ■canic breccia ("trachyte-conglomerate"), with which 

 are associated well-banded acid lavas (trachyte). In 

 -other parts of the island a greenish tuff occurs, which 

 is abundantly penetrated by an interlacing system of 

 basaltic dykes. 



Changtau Island, a rugged island with a double- 

 peaked summit, shows, along its west coast, cliffs con- 

 sisting of a stratified green tuff and trachyte-breccia, 

 -with dykes of basalt and flows of a well-banded trachytic 

 lava. 



Taeskan Island, a series of high hills attaining to a height 

 of 700 feet, connected by broad alluvial plains, consists on 

 its north-east coast of a grey quartz-porphyry, weathering 

 blood-red, and salmon-coloured felsites, penetrated by 

 numerous dykes of basalt. 



Show Island is formed entirely of a coarse trachyte- 

 ibreccia, containing large angular fragments. This rock 

 is much quaiTied, the stone being conveyed away in 

 junks. 



Volcano Island, the most westerly of the chain, is 

 composed of the same volcanic breccia, associated 

 here with felsitic lavas. 



North-East Islet, off Chusan Island, and Nine-Pin 

 Rocks are composed of a compact dark-coloured felsite, 

 with a marked bedded character. In places the rock 

 shows distinct flow-srructure. 



Poo too Island consists of a high peak, separated from a 

 number of smaller ones by deep gullies, filled with blown 

 sand. The summit of the hill is formed of a compact 

 white trachyte, which has been erupted through the 

 granite forming the base of the hill. 



Chusan Island, t^.e largest of the group, being twenty- 

 two miles long and ten miles wide, consists of a long 

 range of mountains, many peaks of which are over looo 

 feet high. Between the numerous spurs given off from 

 these mountains lie tracts of highly fertile land, the lower 

 parts of which have been recently reclaimed, and are 

 protected by a series of embankments. Outside the 

 outermost of these the mud- flats are used for the col- 



lection of salt, to obtain which the mud is scraped up, 

 filtered, and the brine evaporated in wooden trays. The 

 old clifl-line now stands far back from the present coast ; 

 and former islands appear now as isolated hills. This 

 island is less bleak than the smaller ones of the group, 

 owing to the protective influence of the small fir-trees that 

 are encouraged to grow on the hill-sides. Cther trees 

 here met with are the camphor, tallow, maple, 

 and numerous evergreens in the neighbourhood of 

 the villages. The rocks are quartz-porphyries and 

 felsites. 



Lateo Island consists of a coarse volcanic breccia, 

 containing large angular fragments of quar'.z-felsite. 

 This stone is extensively quarried. 



Ketsu Island. — A small rugged double island off 

 Chusan, consisting of dark-banded felsite with sm ill 

 porphyritic crystals of red felspar. 



Blackwall Island.— k large well-cultivated island, 

 with hills of dark-coloured felspar-porphyry and felsite. 

 Volcanic breccia also occurs, penetrated here and there 

 by basalt dykes. 



Kintang Island.— h. large island near the mainland, 

 presenting a fine, pointed summit of red felspar-porphyry. 

 .'\long its cliffs are highly contorted volcanic breccias and 

 felsites. 



Taoutse Island. — A small narrow island of red fel- 

 spar-porphyry (red felsitic ground- mass embedding small 

 bright red crystals of felspar). 



Changpih Island. — A large island with much reclaimed 

 land ; red felspar-porphyry. 



Chinhai Island. — A small rock in the mouth of the 

 Ningpo River, composed of the same red porphyry. 



Rambler Island, Hang-chow Bay. — A rounded mass 

 with steep smooth sides, composed of volcanic breccia 

 and brown felspar-porphyry. 



Mr. Bassett-Smith adds that no traces now remain on 

 the China coast of the volcanic activity that gave rise 

 to the enormous accumulations of lava and tuff referred 

 to in the above notes, with the exception of a few scattered 

 hot springs. He is of opinion that after the eruptions 

 ceased, a subsidence must have taken place, but that the 

 ground is now probably rising. 



WHICH ARE THE HIGHEST BUTTERFLIES? 



THE following extracts from a letter received a few 

 weeks back from Mr. W. H. Edwards, of Coal- 

 burgh, touch on this question, and may be of interest 

 i to lepidopterists. Having now for many years ceased to 

 give attention to this subject, I cannot express any 

 opinion, but I think Mr. Edwards's facts are very 

 curious, and the conclusion expressed in his last 

 paragraph not far from the truth. 



Alfred R. Wallace. 



" In a recent part of my vol. iii. I have figured one 

 of the high Alpine Colorado Ereb'as, E. Magdalena, 

 found on the extreme summits, among nothing but rocks. 

 I have also succeeded in breeding another of the Alpine 

 Erebias, E. epipsodea, from ^^g to imago, and have a full 

 set of drawings for plate. Have also had Chionobas 

 chryxus (also Colorado) and imago, and have all 

 the drawings there. Connected with these Alpine 

 species is a matter I talked over with you, and of 

 which I now write. There must be many genera of 

 Satyridce in which the larvae are thick- bodied, inert 

 creatures, very much like many of the Noctuidoe. I have 

 twice raised Argc Galatea from egg to imago. This larva 

 is remarkably like a Noctuid in shape, inertness, in the 

 manner it lies on the ground— curled up so that head 

 touches tail, in a ring, or like a <i. The pupa is so like 

 a Eudamus, that when I sent one to Mr. Scudder to ask 

 what it was, he replied, ' Some Hesperid probably, very 

 near to E. titvrus.' It is made loose on the ground or 



