FOSSIL DIPTERA. 3 



with the number that have been found on the Continent and in 

 America. 



One of the chief modes of preservation is in amber, the greater 

 number of species having been found in this state. The earliest 

 recorded occurrence of Diptera is in the Mesozoic period, although 

 insects appeared in the early Palseozoic period. The extreme 

 fragility of insects renders their preservation difficult, and we therefore 

 find but a very scanty representation of the Dipterous fauna. It will 

 be only possible here to give a short account of the genera, many of 

 which are described only from such fragmentary remains as wings 

 and other detached portions. 



a.—BRACHYCERA. 



Fam. Dolichopodidcz. — The members of this family are very abund- 

 ant in the fossil state, being beautifully preserved in amber. Particular 

 attention has been paid to these by Loew, who has enumerated 

 nearly seventy species of Dolichopiis, Rhaphium^ Foilopus, Afedeferi/s, 

 and Chrysotus. The genus Dolichopus has also been described from 

 Wyoming. 



Fam. Empidc^. — This family has been figured by Brodie from the 

 Wealden of England ; and, according to Giebel, the species described 

 belongs to a new genus — Hasmona. 



Loew has described the genus Einpis from the Rhenish coal and 

 sixteen from amber. Giebel, Heer, and Loew have described many 

 other genera besides these from the amber of the Tertiaries. 



Fam. Bombylidce. — Alone found in the Tertiaries, the genus 

 Anthrax being found at Oeningen and on the Rhine. They are 

 mostly found in amber. 



Fam. Asilidcs. — Brodie describes an Asilus from the Lower Lias, 

 and Germar another {Asilicus) from the oolite of Solenhofen. These 

 are the only two recorded Mesozoic species. In amber the Asilidse 

 are more abundant. ]\Iany are described from Oeningen and in 

 Sicilian amber. 



Fam. Leptidce. — This family is rare in a fossil state. One species 

 has been recognised in the Eocene of the Isle of Wight. 



Fam. Tabanidce. — The Swiss geologist, Heer, describes and figures 

 one of this family from Oeningen, and it is also reported from the 

 Rhenish coal. 



Fam. Stratiomyidce. — Both perfect insects and larva; have been 

 found in the Tertiary and Quaternary deposits. They have mostly 

 come from Aix, where Serres recognised Oxycera and Sai-gus. 



