THE ENTOMOLOGIST. 



Vol. LV.] MARCH, 1922. [No. 706 



THE FOSSIL SAWFLIES OF FLORISSANT, 

 COLORADO.* 



By T. D. A. Cockerell. 



The sawflies, owing to their position near the base of the 

 Hymenopterous series, are of more than ordinary interest to the 

 evolutionist. Primitive Siricoids are known from far down in 

 the Mesozoic, but, except at Florissant, tertiary sawflies are rare. 

 The remarkable Oligocene deposit at Gurnet Bay, in the Isle of 

 Wight, has produced a long series of Hymenoptera, but not a 

 single sawfly. In the famous Miocene deposit at (Eningen in 

 Baden a few species have occurred, only three of them described 

 and named. Others are known from the Oligocene of Aix, 

 Brunstatt and in Baltic amber, and the Miocene of Radoboj, 

 but the species are few and for the most part inadequately 

 known. A primitive Siricoid of large size, preserved in the 

 British Museum, has been described from the Eocene of Bourne- 

 mouth. 



It is only in the Miocene of Florissant that we have a fairly 

 representative extinct sawfly fauna. No less than forty-two 

 species have been described, referable to twenty-four genera. 

 Ten of the genera have been regarded as extinct, Pseudocimbex, 

 Rohwer, and Phenacoperga, Ckll., being placed by Rohwer in a 

 sub-family — Phenacopergin^. The remaining genera are typical 

 Nearctic and Holarctic types, without any suggestion of 

 Neotropical affinities. They are Janus, Megaxycla, Neurotoma, 

 Hemichroa, Dineura, Pteronus, Eriocampa, Pseudosiobla, Macro- 

 phya, Tenthredella, Schizocerus, Selandria, Cladius and Erio- 

 campoides. It is evident that the modern sawfly genera have 

 £ome down practically unaltered from the Miocene, but many 

 genera once associated with them have died out. 



The genus Cimbex and a new species of Eriocampa may now 

 be added to the Florissant list, the specimens being in the 

 Colorado Museum of Natural History in Denver. I am indebted 

 to Director J. D. Figgins for permission to describe them. A 

 Cimbex larva was reported by Menge as occurring in amber, but 

 otherwise the genus has not been known fossil. 



* Sawflies are known as Hymenoptera Phytophaga, but the adults have been 

 found in the act of devouring other insects. Thus at Brainerd Lake, Colorado, 

 I found Labidia alienata, Bohwer, preying upon Bibio nervosus, Loew (det. 

 Aldrich). 



ENTOM. — MARCH, 1922. P 



