114 



KNOWLEDGE. 



[May, 1901. 



carried out on similar methods, and that the Antarctic 

 area will, within practicable limits, be divided up be- 

 tween them. The British Expedition will be com- 

 manded by Capt. R. F. Scott, and Professor J. W. 

 Gregory of Melbourne University will be chief of the 

 scientific staff. The other members of the scientific 

 staff already appointed are Dr. Koettlitz, surgeon and 

 geologist; Mr. E. A. Wilson, also a sui-geon, who com- 

 bines with a good scientific training considerable 

 artistic power; and Mr. Hodgson, of the Plymouth 

 Biological Station, who will devote himself mainly to 

 the zoological work. Captain Scott will have under liim 

 Lieut. A. B. Armitage, k.n.r., who lias had three years' 

 experience in Eranz Josef Land, Lieut. Royds, h.n., 

 Mr. Reginald Skelton, r.n., and two others not yet 

 appointed. The crew, it is hoped, will consist of blue- 

 jackets. The Gei-mau expedition will be under the 

 charge of Professor von Drygalski, who will have four 

 scientific assistants, a captain, a first oflicer, two mates, 

 and a crew, making twenty-eight in all. The " Discovery," 

 the sixth ship of her name, is somewhat larger than the 

 " Gauss," having a displacement of 1750 tons as against 

 the 1450 tons of the German ship, and a length of 172 

 feet as against 151 feet. The " Discovei-y " will be 

 capable of steaming 8 knots, and the " Gauss " 7 knots, 

 but both ships will use their sails whenever possible 

 for the purpose of saving coal. The ships are extremely 

 strongly built in order to withstand the ice pressur,-^. 

 oak and greenheart being the timbers mainly used. On 

 both ships each officer is to have a separate cabin fitted 

 with evei-y possible appliance to secure comfort and 

 sanitation, and equal care will be taken with the cjnar- 

 ters of the crews. The " Discovery " will have cabins 

 for special purposes ; laboratories for the biologists on 

 deck ; and others for 23hotographic and other purposes 

 below ; the mainyard is to be fitted with a block for dredg- 

 ing opei-ations ; a special magnetic observatory will be 

 constructed on the upper deck, and no iron will be used 

 within thirty feet of it ; she will carry five boats, twenty 

 sledges and twenty dogs, and will be well su.pplied with 

 every sort of amusement and appliance to make life as 

 pleasant as possible through the long Antarctic night. 

 The " Gauss " is also to be provided with laboratories 

 and other special arrangements for scientific work. As 

 far as possible the use of ii'on has been avoided in her 

 construction, in the interest of the magnetic observa^ 

 tions, and its place is taken by copper whenever feasible, 

 and where this could not be done the iron has been 

 coated with zinc. She will carry a windmill, material 

 for a dwelling house, and fovu- observatories ; a captive 

 balloon, fifty dogs, and a naphtha and other boats. Both 

 ships will be fitted with electric light, and will can-y 

 pi-ovisions for three years. 



THE INSECTS OF THE SEA. -III. 



By Geo. H. Caepenter, b.sc.(loni>.), Assisfani hi the 

 Mnseiim of Si'ience and Art, Dublin. 



BEETLES. 



Beetles are so very numerous, dominant, and widespread 

 in all parts of the world and in all sorts of localities 

 that the presence of a fair nvimber by the tidal margin 

 might reasonably be expected. And although if indi- 

 vidvials be counted up, marine beetles will probably be 

 found fewer than marine spring-tails, it is likely that in 

 the number of kinds that occur, beetles outnumber all 

 other insects, except possibly the flies, by the searshore, 

 as they seem to do in the world at large. 



The general fonn of a beetle is known even to those 

 who have never studied in detail the structure of insects! 

 The most characteristic feature is the modification of 

 the forewings into firm plates of leathery or horny tex- 

 ture, to serve as shields — " wing-cases '' or elytra — for 

 the membranous hindwings — alone used in flight — which 

 can be folded beneath them. Beetles thus form an easily 

 recognised order of insects — the " Sheath-wings " or 

 Coleoptera. And the folding up and putting away of 

 the wings beneath their horny sheaths, as jjractised 

 liabitnally by beetles generally, is suggestive of the fact 

 that many beetles have entii-ely lost the power of flight. 

 As a group the beetles have largely forsaken an aerial 

 for a terrestrial life. Their armour-like coats, and the 

 frequently flattened form in very many of the families, 

 correspond with a life on the ground beneath 

 stones, and in such concealed lurking places. Con- 

 sequently adaptation to tidal conditions is less 

 difficult to beetles than to typically aerial insects, 

 and hence the largei number of marine represen- 

 tatives of the order. Among the spring-tails we found 

 that several large genera have each several species 

 adapted for life on the sea-shore. The same state of 

 things occurs among the beetles, but here the adaptation 

 has proceeded further, since we shall find not species 

 only but genera entirely confined to the tidal margin. A 

 high degree of specialization for marine life has, there- 

 fore, been reached by many beetles. 



It is well known that beetles undergo a " complete " 

 transformation, the young insect being hatched from the 

 egg as a grub or larva — wingless, and more or less tinlike 

 its parent, and attaining the perfect state only after 

 passing through a period of rest as a pupa, in which 

 the form of the organs of the future beetle can be clearly 

 made out. There are many interesting steps in the 

 progress towards a truly marine life that can be 

 studied among the beetles. In the great family of the 

 Leaf-beetles Chrysomelidse), there is a genus (Donacia) 

 whose species, fovxnd on freshwater plants, spend most 

 of their time entirely submerged. Their grubs live at 

 the bottom of the water, feeding on the roots of aquatic 

 plants, and they are provided with two spines on the 

 eighth abdominal segment, by means of which they pierce 

 the roots and breathe from the air-spaces enclosed 

 therein.* An allied genus, Haemonia, has a species 

 //. C'urtisii, Lac, found in brackish water on that charac- 

 teristic marine plant the grass-wrack (Zostera). A 

 similar jDrogress towards life in the sea can be traced 

 in other groujDS of water-beetles. The Gyrinidse or 

 " Whirligig " beetles, whose quick mazy dance on the 

 surface of ponds and streams is well known, have a species 

 {Gyrinus viarinus, Gyll.) which is ttsually found in 

 brackish water, though it also occurs in inland, fresh- 

 water localities. Among the aquatic beetles of the 

 family Hydrophilidse — characterised by the unusual 

 length of the palps or jaw-feet of their first maxilla?, 

 and their remarkably short feelers, the genus Ochthebius 

 has several species, which frequent brackish ponds 'and 

 ditches near the coast, and others which haunt stagnant 

 rock-pools that are, at least dtiring the high spring-tides, 

 washed out by the rising sea. 



Many of these Ilydrophilidce are not truly aquatic in 

 their habits, but live in marshy places and damp decay- 

 ing matter. To this section belongs the genus Cercyon, 

 which has two species (C. littoralis, Gyll., and C. 

 depressus, Steph.) inhabiting the sea-coast, and often 



* L. C. Miall. " Tlio \:ituriil Historv of Ai|iiafip Insects.'' Lonilnii 

 )89.') (pp. 93-96). 



