MORGAN HEBARD 105 



of distribution is the foot of the mountain Iwundaries formed by 

 the Cascade, Sierra, Tehachapi, San Galjriel, San Bernardino 

 and San Jacinto Mountains, but near the Mexican border, in 

 the vicinity of San Dieo;o, it invades the coastal region through 

 the Cuyamacas and other lower mountains. In that semi-arid 

 region only, the ranges of .1/. oregonensis Bruner and manni 

 overlap. 



It is noteworthy that, though »tanni is probably widely dis- 

 tributed through the plateaus and mountains of Arizona and 

 adjacent regions, it apparently does not occur anywhere in the 

 mountains forming the western boundaiy of its distribution, 

 those mountains being the habitat of oregonensis, as are the 

 coastal regions westward of them. 



We find that manni is distinctive, when compared with ore- 

 gonensis, in being very pale in general coloration. i'' Schimmer 

 was incorrect in supposing manni to be a very distinct species, 

 recognizable particularly by the lack of minute scales. The 

 alcoholic material which he had before him had been shorn of 

 scales, due probably to washing about in the preservative. A 

 large number of the present series, similarly })reserved, are 

 before us and exhibit the same condition, the series, however, 

 showing plainly the reason. The caudal tibial spines are usually 

 proportionately somewhat shorter than in oregonensis. This weak 

 feature and the pale coloration are the only specific diagnostic 

 characters we can find to separate manni from that species. 



Though fully aware of the weakness of general coloration as a 

 specific diagnostic character, the large series of these two species 

 before us are each so generally constant, oregonensis dark, manni 

 pale, that we believe it best to recognize manni as a valid species, 

 rather than consider it a geographic race of oregonensis or an 

 absolute synonym of that species. 



We would note that in Arizona the distril:)ution of manni 

 coincides with the westernmost known distril)ution of M. nebras- 

 censis Lugger. 



'•^ The light coloration is evidently not governed by the usually pal * sur- 

 roundings of the desert or semi-arid environment of the species. This is 

 shown by the character of the environment in which we found manni and 

 the pale condition of nebrascensis at Grand Canyon Station and Ash Fork, 

 Arizona. See remarks under material recorded. 



TRANS. AM. ENT. SOC, XLVI. 



