COLEOPTERA. — DYTICIDy^. 101 



Straight in front. The legs are rather long, slender, and ciliated on the 

 inside, serving as oars when swimming quickly ; the body is carried in 

 a straight line, but when they stop to breathe or to seize their prey, they 

 assume the shape of the letter S. During the summer the larva is said 

 to attain its full size in about fifteen days, and then quits the water and 

 creeps into the neighbouring earth, where it forms, with considerable 

 skill, around cell, in which, in about five days, it changes to a pupa of a 

 whitish colour, with two obtuse points at the extremity of the body. 

 It appears in the perfect state in about a fortnight or three weeks ; 

 those individuals, however, which became pupae in the autumn, do not 

 appear as Beetles until the following spring. The Beetle is at first soft 

 and yellowish, but it soon hardens and becomes darker coloured ; it is 

 not, however, until the end of eight days that it has acquired its proper 

 consistency. Figures of the larva and pupa of Dyticus marginalis are 

 given by Rosel, Insect. Belastif/. vol. ii. ; Ins. Aquat. tab. 1. ; Lyonnet, 

 Posth. Memoires, vol.i. pi. 11. ; Swammerdam, Book of Nat., pi. 29.; 

 Mouffet, p. 320. ; Kirby and Spence, vol. iii. pi. 18. f. 5. See also a 

 Memoir by Lancret and Miger in the Bullet. Soc.Philom. No. 32. In the 

 Transactions of the Entomological Society of London (vol. i. p. 86.), it is 

 stated that the larva of a Dyticus had been forwarded to Mr. Curtis, 

 which had been voided by a female who had been long subject to con- 

 vulsions. 



The larva of Cybister Roselii (figured by Rosel, loc. cit. tab. 3.), 

 is longer and more slender {Jig. 3. 15.) than the preceding; the front 

 of the head has thin pointed processes, the central one being supposed 

 by Rosel, but evidently erroneously, to be the rostrum ; the extremity 

 of the body is also destitute of the two pilose appendages above de- 

 scribed, and the corresponding caudal tubercles of the pupa are wanting, 

 the head of the latter is also furnished with a transverse ridge, having 

 several small teeth on its edge. 



The larva of Acilius sulcatus (7%. 6. 4. Rosel, loc. cit. tab. 3., and 

 De Geer, vol. iv. tab. 15.) is much smaller than that of Dyt. mar- 

 ginalis ; its head is rather longer behind, and the first segment of the 

 body is considerably lengthened, forming a narrow neck ; the body is 

 more continuous, the segments not being separated by incisions ; the 

 neck is generally bent downwards, and the head turned rather upwards, 

 the parts of the mouth having also the latter direction, so that the 

 animal has the appearance of a small snake. It is extremely in- 

 sidious in its attacks ; the position of the neck and head inducing 



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