HARDWICKE'S SCIEN CE- GOSSIP. 



151 



INSULAR ENTOMOLOGY. 



THE views of Mr. Darwin respecting the changes 

 which insects undergo under insular condi- 

 tions, and where islands have been for a long time 

 separated from mainlands, have been abundantly 

 borne out by the researches of the naturalists 

 attached to the Transit .of Venus Expedition to 

 Kerguelen's Island. This island lies in the Southern 

 Indian Ocean, and was discovered by the Erench 

 navigator Kerguelen, in 1772, by whom it was con- 

 sidered to be a projecting part of the southern 

 continent. A mountain-range, attaining the height 

 of 2,500 feet, runs across the island south-westerly. 

 The island is deeply indented with bays and inlets, 

 and numerous lakes abound ; but the physical and 

 geographical conditions do not seem to be much 

 diversified. Its botany, which is rather meagre, 

 was studied during Ross's Antarctic expedition, but 

 the report of the Rev. A. E. Eaton, M.A., the 

 naturalist to the recent expedition, which has just 

 been published in the "Proceedings of the Royal 

 Society," gives a fuller and more philosophical 

 view of the natural history, especially of the ento- 

 mology, of the island. From this we give the 

 following extract. 



Mr. Eaton says the entomology of Kerguelen's 

 Island is very interesting. " Most of the larger 

 insects seem to be incapable of flight. I have found 

 representatives of the orders Lepidoptera, Diptera, 

 Coleoptera, and Collemboia. The Lepidoptera com- 

 prise a species of the Nocturna (as 1 suppose) and 

 one of the Tineina. Of the first I have not reared 

 the imago ; the larva is a moss-eater and subter- 

 ranean; the adult is probably as large as an 

 Jgrotis of medium size. The species of Tineina is 

 probably one of the Gelechiida;, judging from the 

 form of the palpi. Its larva feeds on young shoots 

 of Festuctc, and sometimes spins a silken cocoon for 

 its pupa. The imago, of which the sexes are alike, 

 has acute and very abbreviated wings, and the 

 posterior pair extremely minute. In repose the 

 antennae are widely separated, and almost divari- 

 cate. When the sun shines the adult is active, and, 

 if alarmed, jumps to a distance of two or three 

 inches at a time. During its passage through the 

 air the wings are vibrated. 



" The Diptera are represented by species of the 

 Tipulidce and Muscidce. There are three of the 

 former family. One of them is a species of Ceci- 

 domyiidae, which is abundant in mossy places, and 

 presents no marked peculiarity. Another seems to 

 be a degraded member of the Tipulidce. The 

 antennse have six joints, the palpi two ; the wings 

 are ligulate and very minute. It possesses halteres, 

 and the female has an ovipositor enclosed in an 

 exposed sheath. Although it is unable to fly, it 

 lives upon rocks in the sea, which are covered at 

 high water, and there it deposits its eggs in tufts of 



Enter omorpha. The third species has full- sized 

 wings. It was caught in the house. The indige- 

 nous Mnscidce are very sluggish in their movements, 

 and are incapable of flight. Four species are 

 common. One of them is abundant on Tringled, 

 crawling over the leaves. When it is approached 

 it feigns to be dead, and, tucking up its legs, drops 

 down into the axils of the leaves. Or, if it happens 

 to be thrown upon a plane surface, one need only 

 look at it closely, and it throws itself promptly 

 upon its back, and remains motionless until the 

 danger is over, when it gradually ventures to move 

 its limbs, and struggles to regain its footing. Its 

 wings are represented by minute gemmules, and it 

 possesses halteres. The ovipositor is extended, its 

 apical joint alone being retracted. The larva feeds 

 upon decaying vegetable matter. Another species 

 occurs on dead birds and mammals, as well as 

 beneath stones nearest the highest tide-mark. It is 

 completely destitute of even the vestiges of wings 

 and halteres. It and the preceding species are 

 rather smooth. A third species, slightly hairy, is 

 common amongst tide refuse, and on the adjacent 

 rocks, which are coated with Euteromorpha, on 

 which plant the larva feeds. It has very small 

 triangular rudiments of wings, slightly emarginate 

 near the apex of the costa, and possesses halteres. 

 The fourth species occurs amongst grass growing 

 on the sea-shore, and also in Shag-rookeries. Its 

 linear and very narrow wings are almost as long as 

 the abdomen. It can jump, but cannot fly." 



Coleoptera are not uncommon. The larger species 

 seem to have their elytra soldered together. There 

 is a small species of the Brachelytra. Two species 

 of Podtirce, one black and the other white, are 

 plentiful. There appear to be few 'species of 

 spiders, though individuals are numerous. Penguins 

 and some of the other birds are infested with ticks. 

 The remaining arachnids are related to Cribates. 

 The plants in Kerguelen's Island are apetalous and 

 self- or wind-fertilized — a fact correlated with the 

 windless condition of the insects, which is believed 

 to be due to the general high winds prevailing, and 

 which would carry winged insects out to sea, and 

 so destroy the species, unless the wings became 

 aborted. 



DIATOM COLLECTING. 



AS the beauty of mounted diatoms depends in a 

 great measure on the cleanliness of the 

 original gathering, sand and other impurities being 

 difficult to get rid of in after-manipulation, I have 

 found the following addition to the ordinary col- 

 lecting apparatus, of very great assistance. It has 

 the advantage of being easily made, and with its aid 

 much better, results can be j obtained than by any 

 other means. 



