524 Metamorphosis of a Species of Cassida, 



128 



which surround the lower margin of the abdomen. The tail, 

 at first sight, appears to constitute a natural and inseparable 

 part of the larva. It is, however, formed by accumulation 

 of the faeces, which, when ejected, are received and retained on 

 a sort of fork, springing from the apex of the body, and form- 

 ing a screen over the insect during this state of its existence. 



This faecifork (to use the term that eminent entomologist 

 Mr. Kirby would give it) is movable on the point of the 

 anus, as on a pivot, and turns the screen it supports in any 

 direction. If this screen or guard is broken off, another is 

 formed in the course of a day. When the change to the pupa 

 state is near the larvae cease to feed, the faecal formation is 

 stopped, and the shaggy screen soon disappears. On the I6th 

 of July several pupae were completed, and on the 23d appeared 

 the insect in its perfect form. 



It is of a rounded oval figure, six lines in length, and fiwe 

 in breadth. The thorax and margins of the elytra are white, 

 and so thin, that the forms of the legs are seen through them ; 

 the middle portion of the shield is brown, with broad margins 

 of black, and the same colour extends in broad arms to the 

 margin on each side, both above and behind ; the anterior 

 spots touch the points of the shield. A single tubercle marks 

 the middle of the shield in front. The antennae consist each 

 of eleven articulations, and are subclavate ; the two terminal 

 ones are black, the rest white; the basal joint longest, the 

 second shortest, the eleventh, or last, pointed. The under 

 side of the body is white, the legs are white, except the 

 tarsi, which are rufous. The eyes are black ; a black spot 

 marks the mouth, and a rufous margin surrounds it. 



I am. Sir, &c. 

 Clapham, June 30. 1829. T. H. 



