1916.] NATURAL SCIENCES OF PHILADELPHIA. 165 



\Y rights ville, Esle of Palms, Tybcc Island, 



N.C. S. C. Ga. 



9 <? o* 9 



Length of body 27.8 17.4 19.3 26.2 



Length of pronotum I '.» 3.4 4. ">. 



Length of tegmen..' 21.9 15.7 It). 7 21.5 



Pablo Beach, Cedar Keys, Galveston, 



Fla. Fla. ' Tex. 



c? o". 9 o" 9 



Length of body 20.3 20. 27. 18.5 23.7 



Length of pronotum 4.1 4.1 5. 3.8 4.5 



Length of tegmen 18.1 16.9 22.8 . 16.3 18.6 



Virginia Point, Corpus Christi, 

 Tex. Tex. 



<7 9 9 



Length of body 21.1 27.5 26.8 



Length of pronotum 5.2 5.3 5. 



Length of tegmen '. 17.5 23.4 20.8 



The Isle of Palms male was taken among the dunes of a barrier 

 beach, entirely away from the true salt-marsh habitat, which may 

 account for the small size of the specimen. The specimens from the 

 vicinity of salt pans with Salicomia and similar vegetation, a type of 

 situation where the species occurred at Galveston and Corpus Christi, 

 exhibit, as the measurements above show, a somewhat depauperate 

 form when compared with specimens from the salt marsh, which is 

 the typical habitat of the species. Apparently the action of environ- 

 ment is seen in these beach specimens in the reduction of wing length 

 and to a certain degree in the coloration, both of which are similar 

 to the condition found in the allied 0. halophila, which as far as 

 known invariably frequents the vicinity of salt pans. Tegminal 

 length as a general thing is a somewhat variable factor in 0. olivacea, 

 the Tybee series showing one female with a body length of 33.3 mm. 

 and a tegminal length of 25, while in this respect almost as much 

 variation either way from the measured specimen is found in the 

 same sex in the Virginia Point series. The general bulk and pronotal 

 length, however, follow the rule laid down above, the influence of a 

 somewhat changed environment on the beaches and flats resulting 

 there in a general size reduction, accompanied by a tegminal abbre- 

 viation much as in 0. halophila which frequents the same habitat. 



The range of this species, so far as known, does not extend south 



of Cedar Keys, Florida, and Corpus Christi, Texas, at the latter locality 



the species occurring with 0. halophila (see below), which replaces 



it southward. Texan olivacea are inseparable from eastern coast 



specimens, and similarly south Florida and south Texas halophila 



are inseparable. 

 12 



