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Psyche 
[Vol. 92 
berryi of the Tennessee Eocene, long considered to be a ponerine, 
was recently placed in the horntail family Pseudosiricidae by Smith 
(1978) and by Rasnitsyn (1980). F. M. Carpenter, the original des- 
criber of this species, concurs with this placement (Carpenter, per- 
sonal communication). Finally, a winged queen found in the mid- 
Eocene oil shales of Messel, Germany, has been placed in either the 
Dolichoderinae or Formicinae by Gahl and Maschwitz (1977). This 
is a reasonable approximation, but the specimen is so poorly pre- 
served that an alternative subfamily assignment — even to some as 
yet unrecognized, extinct group — cannot be excluded. 
It is clear, then, that in order to understand the key events of ant 
evolution the most crucial time frame in which to study fossils is the 
Upper Cretaceous to Middle Eocene. I report here two recent 
important finds: the first ants from the Cretaceous amber of Can- 
ada, representing a new species of Sphecomyrma; and a small sam- 
ple of workers from the mid-Eocene amber of Arkansas, repre- 
senting three of the most advanced subfamilies of ants (Myrmicinae, 
Dolichoderinae, Formicinae). 
Sphecomyrma canadensis, new species 
(Figs. 1,2) 
Diagnosis. Closely resembling S.freyi of the New Jersey amber 
(Magothy Formation, mid-Cretaceous) in most of its visible traits, 
differing in its smaller size (Head Width of holotype 0.66 mm as 
opposed to 1 .00 mm in freyi), somewhat more robust alitrunk, and 
proportionately shorter third funicular segment (which is about as 
long as the second funicular segment, as opposed to slightly more 
than twice as long in freyi). 
Holotype worker. Head Width 0.66 mm, Head Length 0.66 
mm, Scape Length 0.50 mm, length of alitrunk 1.32 mm. A rela- 
tively well-preserved worker collected in situ in the Cretaceous 
“Canadian amber” deposits near Medicine Hat, Alberta. J. F. 
McAlpine, CAS 330, deposited in the Biosystematics Research 
Institute, Ottawa, Canada. 
Paratype worker. Length of alitrunk 1.57 mm. A poorly pre- 
served worker in the Medicine Hat amber provisionally placed in 
the same species as the holotype. J. E. H. Martin and J. F. McAl- 
pine, CAS 205, deposited in the Biosystematics Research Institute, 
Ottawa, Canada. 
