25S 



HARDWICKE'S SCIE N CE-GOSSIT. 



cepting, of course, those that are internal feeders or 

 miners, with regard to whicli we are rather in 

 ignorance. Tliat the familiar silkworm {Bomhyx 

 mori) casts its skin thrice, is certain ; and various 

 as have been the records giving details of its life- 

 history, I am not aware that any breeder of silk- 

 worms has found the number of changes more or 

 less, however the insect might be reared. Yet the 

 idea has been thrown out, that in the case of some 

 Lepidoptera at least, a short or abundant supply of 

 food, or a high or low temperature, may have an 

 influence in producing more or fewer changes of 

 skin during the larval life. If not, indeed, one is 

 obliged to suppose some carelessness on the part of 

 observers, since published accounts vary. The Puss 

 Moth, for example, is said by some to cast its skin 

 thrice; others state that the number of changes is 

 four; the latter has been given as the number in 

 Bomhyx pernyi, though in caterpillars that I have 

 just reared belonging to that species, there were 

 but three. It is rather astonishing, also, to read 

 that Mr. Newman fed up a caterpillar of the Poplar 

 Hawk-moth, and never saw it cast its skin at all. 

 It should be added, that as far as my experience has 

 gone (a not very extensive one) in caterpillar rear- 

 ing, I have noticed a uniformity in ecdysis in the 

 species that I have had from the egg.—/. R. S. C. 



How THE PtJFPIN ASCENDS TO ITS NeST.— lu 



the September number of The Zoologist, Mr. H. M. 

 Wallis has a short note on the above subject. He 

 says :— Considering its habits, the Puffin, in com- 

 parison with most birds building on heights, seems 

 somewhat insufficiently provided with the means of 

 getting to its nest. How it contrived during the 

 breeding season to make the frequent ascents ueces. 

 sary whilst feeding its young, was a question tome, 

 until a short visit to Plamborough Head in June 

 last explained the process. On the cliffs north of 

 the lighthouse numerous guillemots and puffins 

 were nesting. The latter chose the lower clifl's, and, 

 from their boldness, their actions were easily 

 watched both from above and below. Their manner 

 of ascending to their nests, which were from 50 to 

 100 feet from the sea, was as follows : — The bird 

 rose from the water some way from the shore, flying 

 so as barely to clear the tops of the M'aves until 

 within fifty yards from the cliffs, when it appeared 

 to depress its tail, which was fully spread, and by 

 extending its webbed feet on either side to nearly 

 double the surface of resistance, its course was 

 changed, and the bird rose without any apparent 

 difficulty to its nest. Whilst thus used, the legs 

 were laid along the sides, the inner toe of the ex. 

 tended foot was covered by the outer feathers of the 

 taU, the points of the toes did not project beyoud 

 the curve formed by the tips of the tail-feathers; the 

 combined arrangement of feet and tail thus forming 

 a short but very powerful instrument, broader in 



proportion than the tails of most birds at that dis- 

 tance from the body. The habit was common to 

 all the puffins which I saw go to their nests, and I 

 think the guillemots used their feet in a similar 

 manner ; whilst rising, the wings were moved with 

 the same regularity as in horizontal flight. It is 

 evident that the use of the tail and feet described 

 must lessen the speed of flight, and the Puffin is not 

 eminent for its flying powers. It seemed as if the 

 bird ^were conscious that it must have plenty of 

 ^'way" on it at the commencement of the rise, and 

 approached the point at which it began to ascend 

 at a great speed. It occurs to me that the weight 

 of the Puffin's body must tell in its favour, if the 

 bird ascends by the momentum gained in its level 

 flight, driving it up an inclined plane of air. If the 

 above explains the peculiar action of the feet 

 described, it may account for the singularly short 

 allowance of tail that many web-footed birds are 

 favoured with. 



Vibratory Motion of Gnats at Rest.— I have 

 never read or heard an explanation of a fact in 

 natural history which many of your readers must 

 have witnessed sometimes ; I allude to the singular 

 vibratory motion exhibited by certain gnats when 

 at rest on walls of outhouses, &c. It is as though 

 they were suffering from some nervous affection 

 which forbade their being still, the motion being a 

 rapid approach to and retreat from the wall on 

 which they rest, their long legs acting as springs. 

 I have more than once excited this motion in gnats, 

 pi'eviou&ly motionless, by gently blowing upon them. 

 That the vibratory motion which then commences is 

 not due to the mere physical effect of the blowing 

 is evident from the fact that it continues for some 

 minutes afterwards, and that it is not caused by a. 

 draught acting upon the insect's body is certain, 

 inasmuch as I have witnessed it in situations 

 absolutely free from currents of air. Why then 

 does the insect indulge in it ? Some insects I know 

 feign death to elude death from their enemies, but 

 why an insect should apparently attract attention 

 by rapid motion is by no means evident. The 

 similarity of the movement with that seen in dead 

 and sucked-Old insects in a spider's web alone seems 

 to me to supply a sort of clue. But then we must 

 attribute too much instinct to the little gnat, surely ! 

 Perhaps some of your correspondents may offer a 

 far more likely solution. — JFindsor Hambrough. 



The Pigmy Whale. — Dr. Hector writes from 

 New Zealand, in the last number of the Annals and 

 Magazine of Natural History, to say he has obtained 

 the calf of this whale {Neohaleena marginata), two 

 feet three inches in length. All the baleen is in 

 situ, so that there is no mistake. The Doctor thinks 

 the animal is not uncommon on the coasts of New 

 Zealand, but it is rarely obtained, as it does not 

 grow to a large size. 



