:^)74 MEJsTAL EVOLUTIOX IX ANIMALS. 



different instinct of laying on the standing corn.* Some hunt- 

 ing spiders, when they have eggs and young, give up hunting 

 and spin a web wherewith to catch prey: this is the case 

 with a Salticus, which lays its eggs within snail-shells, and at 

 that time spins a large vertical web.t The pup?e of a species 

 ol Formica are sometimesX uncovered, or not enclosed within 

 cocoons ; this certainly is a highly remarkable variation ; the 

 same thing is said to occur with the common Pulex. Lord 

 Brougham§ gives us a remarkable case of instinct, namely, the 

 chicken within the shell pecking a hole and then " chipping 

 with its bill-scale till it has cut off a segment from the shell. 

 It always moves from right to left, and it always cuts off the 

 segment from the big end." But the instinct is not quite so 

 invariable, for I was assured at the Eccalobeion (May, 1840) 

 that cases have occurred of chickens having commenced so 

 close to the broad end, that they could not escape from the 

 hole thus made, and had consequently to commence chipping 

 again so as to remove another and larger rim of shell : more- 

 over occasionally they have begun at the narrow end of the 

 shell. The fact of the occasional regurgitation of its food by 

 tlie Kangarooll ought, perhaps, to be considered as due to an 

 intermediate or variable modification of structure, rather 

 than of instinct; but it is worth notice. It is notorious 

 that the same species of Bird has slightly different vocal 

 powers in different districts; and an excellent observer 

 remarks that " an Irish covey of Partridges springs without 

 uttering a call, whilst on the opposite coast the Scotch covey 

 shrieks with all its miglit when sprung."1[ Bechstein says 

 that from many years' experience he is certain that in the 

 nightingale a tendency to sing in the middle of the night or 

 intlie day runs in families and is strictly inherited,** It is 

 remarkable that many birds have the capacity of piping long 

 and difficult tunes, and others, as the Magpie, of imitating 



* Bonnet, quoted by Kirby and Spence, 'Entomology, toI. ii, p. 480. 



t Duges in Anns, des Set. Nat., 2nd series, tome vi, p. 196. 



X F. Smitli in Trans. Unt. Soc, vol. iii, N.S., Pt. iii, p. 97; and De Greer, 

 ([noted by Ivirby and Spence, Entomology, yoI. iii, p. 227. 



§ Dissertation on Natural Theology, vol. i, p. 117. 



II W. C. Martin in 3Iag. of Nat. Hist., N.S., vol. ii, p. 323. 



IT W. Thompson, in Nat. Hist. Ireland, vol. ii, p. 65, says tbat lie has 

 observed this, and that it is well known to sportsmen. 



=** Stuhen-vogel, 1840, s. 323. See on different powers of singing in 

 different places, s. 205 and 265. 



