Aucu^T 20, 1896J 



NATURE 



367 



In India it is found in the centra! parts of India, in the Punjab, 

 in Afghanistan, in Baluchistan. Probably it will be found in 

 Kajputana and Scinde, and perhaps in some parts of the Dekhan. 

 I have never found it in the alluvial plains of Northern India, nor 

 in Bengal. I have just found it in the Eastern Sudan. Probably 

 it exists in most of the deserts of Asia and Africa. The ones I 

 have found all seem to belong to one species. They are of a light 

 straw colour, often with some black above. A black variety is 

 found on the Afghan frontier. The biggest specimen measured 

 l^ inches from the tips of the jaws to the end of the 

 abdomen. They feed on soft insects like moths, and live in 

 holes on the ground. They are very rapid in their movements, 

 and are difficult to catch when on the move. The best way to 

 get them is to put a glass over them when they are lying still in 

 a corner. .\ big matchbox often acts as a good trap. They 

 will run inside it of their own accord. They go up walls, jjosts, 

 trees, in search of insects, and will jump down from a fair 

 height. 



The movements of their jaws when feeding presents a unique 

 sight. The head is small, and the bases of the jaws are bulbous 

 and look like a continuation of the head. When eating they 

 move their jaws alternately, and one gets the impression that 

 the head is jointed and that each side moves alternately. In 

 encounters with spiders, scorpions and centipedes, they usually 

 fare badly. Their belly is so soft, that once caught there, they 

 are done for. Still they are ver)' combative. 



I have often tried to settle the point as to whether their bite is 

 painful or poisonous. But I never could succeed in making one 

 bile a human being. E. Cretin. 



Suakin P'orce, July 12. 



[The genus Galeodes, represented by several species, is known 

 to extend in Africa from Algeria to Egj'pt, thence southwards 

 into Somaliland ; in Europe, from Greece throughout the steppes 

 of South Russia ; in Asia, over the whole of Asia Minor, Arabia, 

 I'ersia, Baluchistan, Afghanistan and Turkestan, and thence 

 into India, where it has been recorded from the following 

 localities : Punjab (Kohat), Rajputana (Bikanir), Gwalior, Delhi, 

 .Secunderabad, (iuntakul near Bellary, Birhbum, Bengal and 

 Madras. — R. I. Po.ocK.] 



Nest-building Amphipod in the Broads. 



It will be remembered that in 1891, Cordylop/tora lucustris 

 was found in great abundance in Ileigham .Sound. On the 6th 

 inst,, after collecting in that locality and downward to Potter 

 Heigham Bridge, I noticed at the bottom of the bottle a Crus- 

 tacean, apparently a Podocerid. On floatinga piece of reed stem, 

 covered with colonies of the hydrozoon, in a vessel of water, it 

 was evident that the colonies were thickly studded with nests, 

 from which, in some cases, the antenn;i; were seen protruding. 

 Several specimens of these Amphipods were secured at once ; 

 and these the Rev. T. R. R. Stehbing, F.R.S., has kindly 

 identified. They prove to be Corophiiuii crassicorne, Bruzelius. 

 A large colony of the Cordylophora has been preserved in 

 formalin, with the nests. On the following day I met with 

 the .same .Amphipod, in considerable numbers, between Acle 

 Bridge and the .\ngel Inn. Henry Scherren. 



9 Cavendish Road, Harringay. N. 



The Effects of a Strong Magnetic Field upon Electric 

 Discharges in Vacuo. 



Some interesting experiments upon the .subject of this note 

 were described in NatI-'RE, July 19. A small addition to those 

 experiments serves to show the connection between the electric 

 conductivity of the tube and the mean free-path-length of the 

 included molecules. 



Using the .same form of Crookes' tube as employed by Mr. 

 Swinton, but provided with the platinum Maltese cross to inter- 

 cept the kathode rays, the shadow of the cross is rotated upon 

 its centre through an angle depending upon the strength of the 

 magnetic field. The motions therefore of the molecules are 

 changed from right lines to spiral lines, and thus their free paths 

 are lengthened — a result equivalent to a further exhaustion of 

 the lube. The primary eft'cct of the magnetic field, observed 

 by Mr. Swinton, was an increase of conductivity in the tube. 

 The two experiments therefore show that the conductivity in the 

 tube increases with lengthening of the free paths. 



By lowering the tube slowly from a few inches above the pole 



NO. 1399, VOL. 54J 



of the electro-magnet down to contact, the shadow of the 

 cross is seen to rotate slowly, and to become smaller as the 

 luminescent cone contracts to the form shown by Mr. Swinton, 

 with the ape.x on the bulb. 



The rotation of the shadow is reversed by reversing the poles 

 of the m.-ignet ; and when the current is reversed in the tube, 

 the green fluorescence appears as a spiral band round the walls 

 of the tube — a right-handed or left-handed helix, according to 

 the polarity of the magnet. Walter Sidgre.wes. 



Stonyhurst College Laboratory. 



THE LIVERPOOL MEETING OF THE 

 BRITISH ASSOCIA TION. 

 "T^HE detailed local arrangements are now progressing 

 ^ rapidly. St. George's Hall, where the reception 

 room and offices will be situated, has just been re-painted 

 and decorated by the Corporation at great cost. The old 

 wooden flooring has been removed so as to expose the 

 beautiful tiled pavement, which has not been seen for 

 many years, and which will not be covered up again until 

 after the meeting. The buildings and rooms allotted to- 

 the various Sections were meiitioned in the former article. 

 The sectional fittings have now been planned out, and 

 will be commenced at once. Separate electric and oxy- 

 hydrogen lanterns will be piovided for all the Sections 

 that desire them. A large lecture theatre, holding over 

 six hundred people, at University College, will be avail- 

 able for joint discussions between the Sections. 



The details of most of the excursions have now been 

 arranged, and a special " Excursions Guide," in addition 

 to the " Handbook," has been prepared. Amongst the 

 excursions, that to the Isle of Man at the conclusion of 

 the meeting will probably take a foremost place, both on 

 account of its general attractiveness and of its special 

 scientific interest. This excursion will extend over five 

 days — from Thursday, September 24, to Monday,, 

 .September 28, inclusive ; and the party will break up 

 into four Sections : (l) Arch;eologists, (2) Geologists, (3) 

 Zoologists, and (4) Botanists, to be conducted by com- 

 petent leaders over those parts of the island which offer 

 special attractions for scientific study. The geology of 

 the island is varied and interesting, especially as regards 

 the dynamic alteration of the older Pahtozoic rocks, the 

 volcanic series and the richly fossiliferous limestones of 

 Carboniferous age, and the wide developments of the 

 glacial deposits; the Prehistoric, Scandinavian, and other 

 early remains are celebrated ; the marine fauna and flora 

 are abundant, and the presence of the Liverpool Marine 

 Biological Station at Port Erin affords facilities for 

 dredging expeditions and other biological work. 



The detailed programme for the four .Sections, which 

 follows, has been arranged by a Committee of the Isle of 

 Man Natural History and ."Vntiquarian Society, acting 

 along with representatives appointed by the Liverpool 

 Executive Committee ; and a special appendix to the 

 Liverpool " Handbook," containing an account of the 

 geology, antiquities, and natural history of the island,, 

 illustrated by a geological map and a chart, has been 

 drawn up by Mr. P. M. C. Kermode, Mr. G. W. Lamplugh^ 

 and Prof Herdman. 



Section I. — .\rch.ii:ologists. 

 Leaders ; Arthur J. Evans, P. M. C. Kermode. 



Thursday, 24. — Arrive by steamer from Liverpool 

 about 3 p.m. Reception by his Excellency the Right 

 Hon. Lord Henniker, Lieut. -Governor, at Government 

 House. Headquarters at Douglas. 



Friday, 25. — Carriages at g.30 a.m. for Braddan (see 

 ancient crosses and alignments), St. Trinian's, then Tyn- 

 wald Hill (see mound, cist, Runic cross, &c.). Lunch at 

 Creg Malin Hotel, Peel, at i p.m. See Peel Castle, 

 round tower, cathedral, and crosses. Drive to Crosby. 



