. An account of British flies (Diptera). Diptera -- Great Britain. 174 AJV A ceo UNT OF BRITISH FLIES. clinging feet. There are also a pair of pediform' appendages figured on the last segment, analogous to those in fig. 37 of CJiironomus plumosiis^ and also four branchial appendages on the same segment, with two tufts of hairs in addition. These larvffi grow rapidly, so that within six or seven days they are four to five times their original length. After the third moult the larva is one third of an inch long, its head becomes smaller, and its feet elongated; the skin acquires a very delicate
. An account of British flies (Diptera). Diptera -- Great Britain. 174 AJV A ceo UNT OF BRITISH FLIES. clinging feet. There are also a pair of pediform' appendages figured on the last segment, analogous to those in fig. 37 of CJiironomus plumosiis^ and also four branchial appendages on the same segment, with two tufts of hairs in addition. These larvffi grow rapidly, so that within six or seven days they are four to five times their original length. After the third moult the larva is one third of an inch long, its head becomes smaller, and its feet elongated; the skin acquires a very delicate rose colour, caused by the development of the pupal skin beneath. The movements of the larva gradually lessen and eventu- ally cease ; it then casts its skin, and the pupal stage is reached. The pupa is three m. long, with long head, described by Grumm as not unlike that of a cat, with 9-jointed abdomen, and the six legs on the thorax, and bent around the wing cases. The abdomen is covered by many small paired hairs and longer single setae. The sides of the abdomen exhibit long dark brown bands, which terminate in the penultimate segment in a small bunch of claw-like processes. On the last but one segment are two apertures, and between and below them a third, the anal orifice. There are also two groups of delicate hairs on the last segment. The thorax is dilated dorsally into a shield covering the head above ; at the sides of the thorax the wing-cases are visible. Prominent pyriform eyes are also seen, between which lie the antennae. Above the head are two thick fila- ments ; these are no doubt branchiae (resembling those seen in the pupa of Corethra plumicornis). No stigmata are of course seen in these aquatic forms. Such is briefly the structure of the Chironoinus larva and pupa observed by Grumm, in which asexual reproduction was observed to take place. We remember in the case of the Cecidomyidcv, the asexual generations were produced by the Cecid larvre (p. 42), and that th
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