XVlii AUTHORITIES. 



Wiedemann, 0. R. W. — Aussereuropaische Zweiflugelige Insecten. 2 vols. 

 Hamm, 1828-30. With plates. 

 " Diptera exotica. Kilise, 1821. 

 " Analecta entomologica. Kilise, 1824. 

 " Achias, dipterorum genus a Fabricio conditum. Kilise, 1830. 



Sjihyracephala (Achias) brevicornis, Say ; described and figured. 

 " Monographia generis Mydarum. (In the Nova acta Academise Na- 

 turse Curiosorum, vol. xv. Bonn, 1831. 4to. With three plates.) 

 Four new species from N. America. 

 Zettekstedt, J. W. — Insecta lapponica, descripta. 1 vol. in 4to. Lipsise, 

 1838-40. 

 " Diptera Scandinavise disposita et descripta. 12 vols. Lundse, 1842- 

 1855. 



Both of these works contain many diptera common to Lapland 

 and the northern parts of the American continent. 



