136 



NATURE 



[April io, 19 13 



on circular cones, which always touch the incident 

 pencil, and the aperture of which varies continuously 

 with the inclination of the crystal. With a plate of 

 mica, a spot was observed which is situated as if it 

 were the reflected image of the incident ray; but it is 

 doubtful whether we may call it "reflected," because 

 other spots are also seen on the same side of the plate, 

 deviating considerably from the "image." Further 

 experiments in this direction are in progress. 



T. Terada. 

 Physical Institute, Imperial University, Tokyo, 

 March 18. 



Fish-eating Habits of a Spider. 



In a lecture delivered to the Natal Scientific Society 

 on November 22, 1911, the Rev. N. Abraham de- 

 described the habits of a spider that he had observed 

 catching and eating fishes. An account of the lecture 

 was printed in The Natal Advertiser and subsequently 

 reprinted in The Agricultural Journal of the Union 

 of South Africa, but, so far as I am aware, these in- 

 teresting observations have not appeared in any pro- 

 minent scientific publication. 



When Mr. Abraham's lecture was given the spiders 

 had not been determined, but I have since had an 

 opportunity of examining two preserved examples in 

 his possession, and I have determined them as Thalas- 

 sins spenceri, Picard-Cambridge (Proceedings of the 

 Zoological Society, 1898, p. 2S). 



The following is an extract from the newspaper 

 account : — " In the year 1905 I was living in Grey- 

 town, Natal. One day I was catching small fish and 

 aquatic insects for an aquarium. I was using a small 

 net in a shallow stream. I happened to see on the 

 edge of the water a fine spider, which I captured. 

 On reaching home 1 placed my specimen in a large 

 aquarium, where I had a number of small fish. The 

 spider measured about three inches when its legs were 

 extended ; the body is small, but the legs are long. 

 After being on the rockwork of the aquarium for some 

 time, it took up a very interesting position. It rested 

 two legs on a stone, the other six rested on the 

 wale]-, well spread out, the ends of the six legs com- 

 manding a definite and well-defined area of water. 



" Being busy, I merely took a note of its attitude, 

 and left it to its devices. After a few minutes mv 

 servant boy came into my study to say that the spider 

 1 had put into the aquarium was eating one of my 

 pet fish. I at once went to see what had happened, 

 and soon saw the spider on top of the rockwork, 

 holding in its grip a beautiful little fish about four 

 times the weight of its captor. For a moment I was 

 startled into a strange surprise. How could this 

 spider, which has no power to swim, catch a lively, 

 quick-swimming fish? I looked at it in wonder, as 

 it seemed to clutch the fish as a cat clutches a mouse. 

 It soon began to devour its catch, and after some 

 time had passed nothing was left of the fish but its 

 backbone. The spider had eaten it as surely as an 

 otter eats its trout. 



" I was now anxious to find out how the spider 

 caught the fish. That night, about n o'clock, when 

 I had finished my day's work, I sat down by the 

 aquarium to watch the spider, with the hope that I 

 might see how the fisherman caught his fish. The 

 spider had taken up a position on a piece of stone, 

 where the water was not deep, and had thrown out 

 its long legs over the water, upon which their ex- 

 tremities rested, making little depressions on the sur- 

 face, but not breaking the ' water skin.' The tarsi of 

 two posterior legs firmly held on to a piece of rock 

 just above water-level, the whole of the body was well 

 over the water, the head being in about the centre of 

 NO. 2267, VOL. qi] 



I the cordon of legs, and very near to the surface of the 

 water. 



"After watching for some little time, I saw a small 

 fish swim towards the stone and pass under the out- 

 stretched legs of the spider. The spider made a swift 

 and sudden plunge. Its long legs, head, and body- 

 went entirely under the water, the legs were thrown 

 round the fish with wonderful rapidity, and in a 

 moment the powerful fangs were piercing the body of 

 the fish. The spider at once brought its catch to the 

 rocks, and began without delay to eat it. Slowly, but 

 surely, the fish began to disappear, and after the lapse 

 of some time the repast was over." 



Recently the Rev. Father Pascalis Boneberg, of the 

 Marianhill Monastery, Natal, has added to Mr. 

 Abraham's observations. Father Boneberg has seen 

 examples of this same spider catching and devouring 

 tadpoles of the toad Bufo carens, and adults of the 

 little frog Rappia marmorata. It is his intention, I 

 understand, to communicate an account of his ob- 

 servations to a German scientific publication shortly. 



That the observations of both these gentlemen are 

 based upon the same species, Thalassius spenceri, I 

 have no doubt, for Father Boneberg allowed me to 

 examine an adult male and female, and two immature 

 examples, of his spider. The two latter specimens 

 he kindlv presented to the Durban Museum. 



E. C. Chubb. 



Durban Museum, Natal, March 15. 



A Detonating Daylight Fireball. 



The following may be of interest to some of your 

 readers. On the morning of February 10, at about 

 a.m., the manager and some of the employees of 

 a sheep farm which is situated on the Coyle River, 

 about seventy miles from its mouth, were working- 

 close to the settlement when they were suddenly- 

 startled by an almost deafening noise which resembled 

 the explosion of a huge gun or a violent peal of 

 thunder close at hand. This was followed by a hum- 

 ming sound, such as would be produced by a motor- 

 car, which lasted for about twenty seconds, after 

 which interval there was another explosion, less 

 violent than the first, which in turn was followed by 

 further hummings and explosions, the latter gradually 

 dying away in about a minute or so. 



These men saw nothing to account for the sound, 

 but as the settlement is situated at the foot of a high 

 hill, which rises to the south, it was their impression 

 that the noise came from over the top of this hill. 

 Later in the day Mr. Welsh, the manager referred 

 to, from whom I had most of the facts, met some 

 carters, who told him that they actually saw the 

 object, that it was about twenty-five miles further 

 down along the same river on the top of the high 

 pampa at the same hour, that it resembled a huge 

 ball of fire with a long tail behind, and passed rapidly 

 from east to west ; they noticed no explosion. 



These facts were corroborated bv a sheep farmer 

 (Mr. Ness), who lives about twenty-eight miles above 

 Mr. Welsh, on the same river. Mr. Ness told me 

 that he did not see the object, but that the sound of 

 the explosion shook all the windows in his house and 

 was followed by the same humming sound and 

 secondary shocks. 



The servant of a neighbour in this town also in- 

 forms me that on the same morning at about the same 

 hour she heard what she considered a series of bombs 

 exploding-. Now Mr. Ness's house is upwards of 

 ninety miles from here, and as it shook his window's 

 it would probably have been heard another sixty 

 miles further on ; this would lead one to believe that 

 (he explosions were distinctly audible over an area 



