T. D. A. Cockerell — Descriptions of Tertiary Insect*. 71 



upper side of quadrangle not or barely longer than inner side : 

 six cells on lower margin before Cu, begins to zigzag, and ten 

 cells in the zigzag portion, making 16 cells in all from subquad- 

 rangle and end of Cn 3 ; three cells between M, and M 2 before 

 the doubling begins ; costa before nodus scarcely at all arched. 

 Florissant : one specimen ; Station 14 iT. D. A. Cockerell). 

 A poorly preserved leaf of Eicus arenaceceformis Ckll. is on 

 the same slab. The figured specimen is in Peabody Museum. 



Fig. 2. Encdlagma florissantella. 



Yale. Some of the characters used to separate fossil Agrio- 

 nines are so variable in recent species as to be of small value. 

 This was pointed out to me by Dr. Calvert, and is very clearly 

 indicated by a series of EnaUagrna very kindlv siren to me 

 by Mr. E. B. Williamson. Thus : 



(1) Cells between M, and M, before doubling begins. A 



specimen of E. antennatum (f.scheri) has three in ante- 

 rior wing, four in posterior. 



(2) Cells between quadrangle and level of nodus (supposed to 



separate the fossil A grion exsirfaris Scudd. from A. masce- 

 scens Scudd., the first having three, the second four). 

 Three is the usual number in Encdlagma. bur E. travi- 

 atum may have four, and in a male E. carunculatum one 

 wing has four, the other three wings three each. 



(3) Length of upper side of quadrangle. It is much shorter 



in anterior than posterior wings of EnaUagma civile, 

 E. antennatv/i/t. E. exsulans. and E. travialum. 



On the other hand, many undoubtedly distinct recent specie- 

 are so similar in the wings that it is exceedingly difficult, to 

 say the least, to separate them by these organs alone. In deal- 

 ing with the fossils, therefore, one may well hesitate to assert 

 that species are synonymous, although some of their assigned 

 characters are likely to be of less than specific significance. 



The Florissant species of this group may be separated as 

 follows : 



Subquadrangle with a cross-nervure in the middle : sub- 

 nodus almost vertical ; first postnodal cell considerably longer 



than second ; eleven postnodal sectors 



" Triehocnemis " aliena Scudder. 



