OETHOPTERA ACE1DIDAE INTRODUCTORY REMARKS. 861 



by Dr. Stal may map the ground into areas whose lines fall wide of those 

 heretofore given ; but before we follow this, we must be convinced that his 

 characters group according to nature. Dr. Gill, if I recollect rightly, 

 remarks, in the introduction to his arrangement of the Fishes, that a charac- 

 ter or series of characters which may be used in one group or even part of 

 it as a correct guide may fail to indicate the true relation of species at 

 another point. Dr. Stal is doubtless fully aware of this fact ; but it appears 

 to me he has neglected at some points to act upon it, and has maintained 

 his plan somewhat arbitrarily. Still I do not feel authorized to take direct 

 issue with him without further opportunity for examination, but simply wish 

 to be understood as saying that the change his arrangement requires in the 

 oroup now under consideration is too great to be made without better 

 reasons shown than those presented in his work. 



Opsomala, Serv. (Opomala, Scudd.), is torn into fragments, and scattered 

 hither and yonder. 0. filiformis and 0. marginicollis, Serv., are placed in a 

 new genus, Leptysma, belonging to Acridiidce, which has no marked or prom- 

 inent character to distinguish it ; that of the head being longer than the 

 pronotum forming one of the principal features. But those who have paid 

 any attention to this group know how unsatisfactory this character is. 



A new genus, Arnilia, is established by the author for the reception of 

 his 0. cylindrodes, with which he places two specimens from Carolina. The 

 latter, I presume, belong to Stenacris chlorizans, Walk. (Mesops chlorizans, 

 Thos.). 



0. bivittata, as Dr. Stal informs me by letter, is probably his Mermiria 

 Belfragii, a new genus belonging to his Truxalidts, and a species from Texas, 

 which he has described as new; but his description leaves it doubtful 

 whether he is correct in this opinion. 



The following changes occur in Truxalidce : Oxycoryphus, Gomphocems, 

 Stetheophyma, Stauronottis, and Epacromia are transferred to this division. So 

 far as this change relates to Oxycoryphus, Gomphocerus, and Epacromia, I can 

 heartily approve of it, and I find, by reference to my notes heretofore men- 

 tioned, that I have already transferred Oxycoryphus, Pedioscertetes, and Cliry- 

 sochraon to Tryxalini. 



The old name Acrida of Linnseus is restored for the typical Truxalides 



