244 



NA 7 URE 



{July is, 1883 



This sandstone is soft and is broken up and rounded into huge 

 boulders, which are covered with ? smooth, chocolate-coloured, 

 ferruginous glaze, deposited by the river, and hardened by the 

 sun. These boulders thus glazed might well have been regarded 

 by Mr. Stanley as trap and lava, &c, while the large grain of 

 the stone, together with the appearance of the blocks in some 

 places might suggest its being granite. This sandstone with the 

 exception of a little which is quartzitic, is the only rock I have 

 seen between Manyanga and Stanley Pool, and is certainly the 

 rock at the great Ntamo cataracts here. 



On the hills and cliffs about the Pool there are some white 

 shining patches, which I hear are sand, but I believe there is no 

 calcareous rock in the neighbourhood. The pool itself is a 

 strange break in the lines of sandstone hills, which, although 

 now much eroded by water, are the remains, doubtless, of what 

 was once a plateau, at the level of about 1500-1S00 feet above 

 the sea. 



On the road to San Salvador from our old Musuka station we 

 find boulders of ironstone and small nodules of the same, mixed 

 with clay, 011 the top of quartz, micaceous, and granitic rocks. 

 Limestone crops up in several places, but the principal formation 

 visible is the ironstone clay. In all this country I have not met 

 with a trace of a fossil of any kind. 



When at Landana, about two miles -outh of the mouth of the 

 Chiloango River, some months ago, I saw some stones from the 

 cliffs which appeared to be almost identical with a Portland 

 stone (?) which I have seen used in fortifications in the south of 

 England. There were many fossils, but I could neither spare 

 time to examine the cliffs nor carry many specimens, being on 

 an express journey by hammock up the coast. This was the 

 only occasion that I have met with any fossils in Africa, and 

 that in a part of the coast now well known through the work of 

 the German Expedition. The quartz, micaceous, slate, shale, 

 and sandstone rocks of this part of the continent are a poor 

 field for palaeontologic research. 



I am very curious as to the geological formation of the Congo 

 Valley between this point and the Stanley Falls, but at present 

 have learned nothing. I should expect, however, to find the 

 sandstone the only visible rock. 



I wish that I could speak with better acquaintance with the 

 names of the rocks, but often I feel sorely puzzled. On our first 

 journey to Stanley Pool we mistook some strangely shaped hills 

 near to Manyanga for granite, but have since a-certained them 

 to be singular relics of the sandstone. 



I need not enter into detads of our work, which are so fully 

 and constantly reported in the Missionary Herald. Regretting 

 that the information I can supply is so meagre, 

 Believe me, dear Sir, yours very truly, 



W. HOLMAN BENTLEY 



Intelligence in Animals 



1. I OBSERVE that Dr. Romanes, in his very interesting work 

 on "Animal Intelligence," has been good enough to notice an 

 account given by me in Nature, vol. xi. p. 29, of an instance of 

 a scorpion committing suicide under special excitement. It may 

 be well to remention the fact that in this case the rays of the sun, 

 focused on the back of the scorpion by means of a common 

 lens, were the exciting cause of the self-inflicted fatal sting ; and 

 to set the matter at rest it may be remarked that two witnesses 

 who saw the experiment can corroborate my statements. On 

 reconsidering the whole affair, however, it occurred to me that 

 in wounding its own back the scorpion may have merely been 

 trying to get rid of an imaginary enemy. The concentrated rays 

 of the sun no doubt caused pain, and the sting was probably 

 directed towards the seat of this in an automatic manner, as a 

 defensive act. This seems to me a more feasible explanation 

 than to regard the action as due to an instinct detrimental to the 

 individual and to the species. 



2. While writing on the subject of "animal intelligence," it 

 has occurred to me that the following remarkable example is 

 worthy of being put on record : — Some years ago, while living 

 in Western Mysore I occupied a house surrounded by several 

 acres of fine pasture land. The superior grass in this preserve 

 was a great temptation to the village cattle, and whenever the 

 gates were open, trespass was common. My servants did their 

 best to drive off the intruders, but one day they came to me 

 rather troubled, stating that a Brakminy bull which they had 

 beaten had fallen down dead. It may be remarked that these 

 bulls are sacred and privileged animals, being allowed to roam at 



large and eat whatever they n ay fancy in the open shops of the 

 bazaar-men. 



On hearing that the trespasser was dead, I immediately went 

 to view the body, and there sure enough it was lying exactly as 

 if life were extinct. Being rather vexed about the occurrence, in 

 case of getting into trouble with the natives, I did not stay to 

 make any minute examination, but at once returned to the house 

 with the view of reporting the affair to the district authorities 

 I had only been gone a short time, when a man, with joy in his 

 face, came running to tell me that the bull was on his legs again 

 and quietly grazing ! Suffice it to say that the brute had 

 acquired the trick of feigning death, which practically rendered 

 its expulsion impossible, when it found itself in a desirable 

 situation which it did not wish to quit The ruse was practised 

 frequently, with the object of enjoying my excellent grass, and 

 although for a time amusing, it at length became tiresome, and re- 

 solving to get rid of him the sooner, I one day, when he had fallen 

 down, sent to the kitchen for a supply of hot cinders, which we 

 placed on his rump. At first he did not seem to mind this much, 

 but as the aoplication waxed hot, he gradually raised his head, 

 to jk a steady look at the site of the cinders, and finally getting 

 on bis legs, went off at a racing pace, and cleared the fence like 

 a deer. This was the last occasion on which we were favoured 

 with a visit from our friend. G. Bidie 



Ootacamund, June 5 



The Mealy Odorous Spot in Lepidoptera 



The mealy spot on the base of the front margin of diurnal 

 Lepidoptera, which emits an odour supposed to serve for sexual 

 purposes, is present only in the male. It is therefore mo-t 

 interesting to observe that this spot is not always present in 

 different individuals of the same species. Among the numerous 

 varieties of Pdpilio priami4s proved by rearing to belong to that 

 species, the spot in question is present only in P. priamus, and 

 is wanting in the male of all the varieties which have come under 

 my observation. Callidryas eubule has the spot present only in 

 specimens from Florida: it is wanting in all specimens from 

 other localities of the United States, including a large number 

 from Texas. In Colias electra and editsa, Keferstein (Wien. Zool. 

 Bo/. Gesell. 1882, p. 451) states that after an examination of a 

 series of malts he has found the mealy spot only exceptionally 

 present, and the same is supposed by him to be the case in other 

 species of Colias. 



It would be interesting to know how this exceptional presence 

 of so prominent a characteristic is to be explained. 



Cambridge, Mass., June 21 H. A. Hagen 



Causes of Glacier Motion 



Unfortunately not having been present when Mr. W. R. 

 Browne read his paper on glacier motion at the Royal Society 

 on Tune 15, 1882, it only came under my notice when published 

 in Nature, vol. xxviii. p. 235. It is doubtless of little impor- 

 tance, but there is one sentence which does not seem to read 

 exactly as I wrote it, namely, " It (a glacier) will get a series of 

 cracks in its longer axis," should be "across (or transverse to) 

 its longer axis," which I think makes the meaning more clear. 



I may perhaps mention that when ice on lakes becomes from 

 four to seven feet thick the effect of a sudden decrease of tem- 

 perature does not, for obvious reasons, always ciuse a complete 

 solution of continuity of the ice all the way through from its 

 upper to its under surface, the crack being wedge-shaped, thus — 



.U 



Ice 1/ Ice 



;y; 



Water 



so thai the water sometimes does not flow into the crack ; the 

 equable and higher temperature of the water counteracting at a 

 certain point of the ice's thickness the penetration and conse- 

 quent contracting influence of the colder air. 



When the ice has acquired the great thickness above men- 

 tioned, the cracks by contraction are never so wide as when the 

 ice is from one to three feet thick, but as far as I can remember 

 they were more numerous, and when the water did not flow into 

 them, were drifted full of snow by the first breeze of wind. 



4, Addison Gardens, July 7 John Rae 



