92 
cc. Tip of the sub-anal plate of the male acumi¬ 
nate and notched, notch sometimes minute but 
never absent. 
d. Essentially and “constitutionally” migratory; 
a little larger than 29 or 30; wings generally 
very long. ((?. spretus.) 31. 
dd. Non-migratory; smallest of the three species; 
notch in the tip of the sub-anal plate not so 
distinct as in 31 (G. atlantis.) 30. 
Remark.—Stetheophyma lineata is omitted from this key, because I 
have no specimen for examination; nor have I attempted to tabulate 
the Tettigi , because of the uncertainty which yet hangs over the spe¬ 
cific distinctions. Pezotettix unicolor is also omitted. 
LIST OF ILLINOIS SPECIES. 
This list includes all the species of Acrididce known to me to in¬ 
habit the State; it is more than probable that other species have been 
discovered, if so, it is hoped the publication of this list may bring 
out that fact. The synonyms are added for the convenience of the 
readers. 
1. Mermiria bivittata , Serv. 
Opsomala bivittata, Serv. Hist. Orth. 589. 
Opomala bivittata, Thomas, Syn. Acrid. 64. 
Mermiria belfragii, Stal, Recens. Orth. I. 102. 
2. Truxalis brevicornis , Linn. 
Gryllus (Acrida) brevicornis, Linn., Syst. Nat. II. 692. 
Truxalis brevicornis, Fabr. Ent. Syst. II. 27. 
f. viridulus, Pal. Beauv. Ins. Orth. 86, PI. 3, fig 4. 
m. notochlorus, Pal. Beauv. Ins. Orth. 80, PI. 3, fig. 3. 
Acridium ensicornu, Deg. Ins. III. 499. PI. 42, fig. 7. 
Opsomala punctipennis, Thos. Trans. Ill. St. Agl. Soc., V. 447. 
Pyrgomorpha brevicornis, Walk. Cat. Dermap. Salt. III. 500. 
Pyrgomorpha punctipennis, Thos. Syn. Acrid. 68. 
3. Chloealtis viridis, Scudd. 
Chloealtis viridis, Scudd. Bost. Jour. Nat. Hist., VII. 455. 
Opsomala brevipennis, Thos. Trans. Ill. Agl. Soc., V. 451. 
Chrysochraon viridis, Thos. Syn. Acrid. 71. 
Truxalis angusticornis, Stal, Recens. Orthop. I. 105. 
4. Chloealtis conspersa. Harr. 
Chloealtis conspersa, Harr. Rep. Ed. 1862, 184 
abortiva, liar. Rep. Ed. 1862, 184. 
Stenobothrus melanopleurus, Scudd. Bost. Jour. Nat. Hist. 
VII, 456. 
Chrysochraon conspersum, Thos. Syn. Acrid, 76. 
