February 7, 1895J 



NA TURE 



^ A *> 



by about 6° ; at 50 fathoms, by 3°7 ; while at lOO fathoms, 

 three of the resi:lts are wiihin o°'3 of one another, the fourth 

 being l'"l ahove the lowest. From ico to 200 f;ithom=, the 

 temperaiureF, diminishing in the same ratio, differ by about the 

 same amount. 



It is HiflTicult to 'ay exactly what value can be placed on each 

 individual observation. Many small errors may creep in ; 

 errors of reading, errors from movement of the indices, errors 

 from insufficient time heing given for the insirumewc to take up 

 the true temperature, &c. 



These should not, however, reach a degree in any instance, 

 and it is pretty plain that below 100 fathoms the temperature at 

 this spot remains fairly equable. This confirms the general view 

 held by Iho^e who have studied the results obtained from obser- 

 vations at different depths, in different parts of the ocean. 



While from one point of view it is unfortunate that the 

 observations have been lalen in different months, on the other 

 band, the vaiiation in the surface temperature at different 

 seasons of the year is given full value in the comparison. 



January 26. \V. J. L. Wharton. 



"The Bird- Winged Butterflies of the East." 

 Permit me to add a few notes supplementary to the very 

 interesting and able article, by my friend Mr. Kirby, entitled 

 " The Bird-Winged Butterflies of the East," which appeared in 

 your issue of January 10, p. 254. 



(0 If the male of eiher of the two species of my genus 

 /Jithci^ftera is examined in the proper light atid position, a long 

 pupse form stigma, composed of raised scent- producing scales, will 

 be very readily seen, of a more slender character, but in nearly 

 the same relative position on the hind margin of the anterior 

 wing, as in the males of the genus Otiii/lio/'lera, or, as Mr. 

 Kirliy pnfers to call it, Ttoi'les. As I have pointed out in 

 part viii. of my " Icones Ornithopterorum," this stigmatic 

 sexual brand, being a densely black mark surrounded by the 

 general velvet black of the wing, is very likely to be overlooked 

 by a casual ob-erver in some positions, while it is really very 

 prominent in others ; and I have called special attention to the 

 lovely arrangements by which the lattrr result is attained ; and 

 a reference to the plates containing the figures of these species 

 will suffice to show how very obtrusive the mark is, and how 

 much more beautiful the insect I'ecomes by the magical play of 

 opalescent tints on the black which encloses the sti^jma, as the 

 insect is moved into different positions against or opposite the 

 light. To sim[>ly look at the insect as it 'tands iti a cabinet 

 drawer, is to mi-s all this glory and its raison d'flrc. As in all 

 the species of Ointthoptera, the female p"ssesses no such organ. 



(2) ^K. (?) Tithoiivi ' Dc Haan), as quoted by Mr. Kirby, is (as 

 he cvidtntly suspect ) not a memter of the genus . Ethcot'tera at 

 all, but belongs to the first genus of the tfue Ornithopien, viz. 

 Schoenbergia(i,\x\> genus of Pagen^techer, and genus of A'///o«) ; 

 and 1 have no doubt that the female hutteifly supposed to be its 

 mate, is rightly assigned 10 it, as it is singularly like the female of 

 Sch. Parailiifit of Staudinger, and also co generic with the 

 large form described by M. Ch. Oberthur under the name 

 O. Goliath. Neither in ScIi Paradista or S<h. Tithoiius is the 

 male furntshcd with a pup^form sexual mark as in Ornithoptera 

 and .^itheoplera^ nor with an abdominal marginal pouch or 

 fold concealing the nndrocoiiia, as in the males of Po/iipcoptera, 

 or a-s Mr. Kiriy calls them, OniitliopUra and 7^roi^oitopteya. 



(3) I am compelled to regard the Ornithoptera as being 

 naturally divided into three sub groups of unequal extent (so 

 far as our present material indicates): (i) The African or 

 Acraoid Ornithoptera, containing one genus {/)riirya), and two 

 specie", D. Anlinuuhui (Drury), and D. /ialmoxis of Hewitson ; 

 (2) the Oriental or true Ornithoptera, with the five genera 

 ScAoenieriia, OruilUoftera, ^El/icoptirra, Troi^onoptera, and 

 Pompioplera ; (3) the South and Central American Ornithop- 

 Urina^ coiraining the numerous black and red, and black and 

 green, and olive black Papilios, which are usually allowed to 

 follow the true Ornithoptera in our systematic catalogues. The 

 males of many of these possess an abdominal marginal fold 

 concealing the androconia^ an organ not found, as far as I am 

 awaie, on the abdominal n.argin of any other section of the 

 Papilionida: — though the sexual stigma can be found on the 

 anterior wings of several males, as tn P. Ulysses for example, 

 though differing in form and position. 



(4) My re.aMins for not adopting Ilubner's name Troides in 

 place of Orttilhoflera for the Pnanius group will be founil by 

 referring to "Icones Ornithopterorum." .\t the same lime, I 



NO. I319, VOL. 51] 



quite understand, and to some extent sympathise, with the severe 

 and uncompromising appliciiion of the law of priority in 

 nomenclature for which .Mr. Kirby and several other naturalists 

 contend. 



(5) The wonderful iridescence of the yellow hind wings of 

 Poinfenplera Magcllaiius, <J , may be seen equally displayed on 

 the unrter surface also. 



Finally, I may safely say that the males of yEthcoflera and 

 Schotiibergia are pro'iably the most perfectly beautiful of the 

 butterflies of the world. ROBERT H. F. Rippon. 



Upper Norwood, .S.E., January 19. 



Thirst-endurance in some Vertebrates. 



Whe.n an example of great ability to endure thirst is desired, 

 the camel is usually suggested. Hibernating animals also are 

 put forward in instance of existence without water for long 

 periods. The camel carries a supply with it, so that what is 

 most wonderful in its case is the tank. Torpid animals need 

 little or no moisture beyonH that in their systems, and, besides, 

 they benefit from dampness around them. Better examples 

 abound on the arid plains near the Rocky Mountains and the 

 Sierras, in the innumerable active, noisy little rodents, miles 

 away from streams or pools, and out of possible reach of water 

 by burrowing. Any one who observes these creatures in their 

 haunts in midsummer, will be pretty sure to inquire, like one of 

 my companions, " What do those little wretches get to drink, 

 anyhow?" The only reply appears to be, "They drink water 

 when they gel it, and do without at other limes," For 

 weeks and months, when the vegetation is shrivelled and parched, 

 and the sand^ are at iheir hottest, these squirrels and their 

 neighbours, with thickening blood, wait for the rain, that the 

 currents in their veins may be thinned and quickened. But 

 one need not go so far for a much belter instance than the 

 camel. The common mouse endures thirst quite as well as its 

 allies in the desert. This has been proved rcpea edly by mice 

 kept here as a reserve supply of food for a lot of reptiles. Re- 

 ducing the allowance of water prevented the foul odour by which 

 mice are generally attended ; this leil to keeping some of them 

 entirely without water, to note the effect. Last winter, a few 

 were kept in a warm room more than three months before being 

 fed to the snakes. On the first of last October, several were put 

 aside to have no drink ; at the lime of writing, three months 

 and a half later, they are eating heartily of the dryest of maize 

 and grass seeds, on which alone they have been fed, and they 

 act as if able to endure the experiment a month orlwo longer, 



S, Garman. 



Cambridge, Mass,, U,S,.-\., January 17, 



Electroscopes in Lecture, 



The electroscope which Prof, Lodge proposes to use to indi- 

 cate pcisitive and negative potentials hy different movements of 

 the leaves (see p, 320), has the disadvantage that (assuming the 

 case to be charged negatively), if too large a negative charge be 

 given to the gold leaves they will diverge, and the inference 

 will be that the potential is zero or positive, neither of which 

 is the truth. For the purpose Prof, Lodge has in view, a 

 Bohnenberger's electroscope would indicate more clearly posi- 

 tive, negative, or zero potential. Instead of the two dry piles, 

 the inner and outer coatings of a charged insulated Leyden jar 

 connected to two knoh.s, one on each side of the single gold 

 leaf, might be substituted. J. Reginald .\SHwnRTH. 



The Owens College, Manchester. 



Snake Cannibalisin. 



Thk notice in Nature, January 31, p. 321, on the above- 

 mentioned subject, calls to my mind the following passage in 

 Rcnan's " .\verroe-," Paris, 1867, p. 310. He refers to the 

 pre-Raph.xlite pictures representing allcgoricaliy the "Seven 

 Liberal .\rts,' and adds: "Dms une fresque ic'remment 

 dccouverte a Puy ... La Log'que tient en main un liizard ou 

 un scorpion. Dans un tableau d'Angelico elle lient diu.x 

 serpents qui se devorenl." 1 have not succeeded in finling any 

 further statement about ihis picture in the books on Art within 

 my reach, nevertheless this may prove an interesting addition 

 to the growing literature on cannibal snakes. 



C. R. OsTKN Sacken. 



Heidelberg, February 3. 



