NO. 1124. EEVISION OF THE MELANOPLISCUDDER. 123 



Plwetaliotes, and Oedaleonotm, each of which is represented by a single 

 species. I have treated this matter more fully in the Introduction. 



The present genus, so richly endowed with species, is naturally very 

 widely distributed, though so far as known it is completely confined to 

 the continent of North America, and even does not occur, so far as 

 reported, 1 south of Mexico. Within this region it is as widespread as 

 all the other genera, combined. It extends from the arctic circle in 

 Alaska and on the Mackenzie River, and from northern Labrador and 

 perhaps southern Greenland on the north, to the extremity of Florida 

 and southern Mexico on the south, and from the Atlantic to the Pacific. 

 It is, however, far richer in species in the west than in the east. Only 

 seventeen of the one hundred and thirty-one species are found exclusively 

 east of the Mississippi River ? though four other eastern species barely 

 cross it; while in the Eocky Mountain region and west of it, and there 

 only, forty-nine* species are known, while thirty-two others are found 

 only west of the Mississippi River and seven western species barely x 

 cross it to the east; six species, as stated in our introduction, range 

 from Atlantic to Pacific; one occurs only north of our national bound- 

 aries in Labrador, while nineteen others inhabit Canada; twelve are 

 found only in Mexico, with ten others which it possesses in common 

 with the United States. 



'These figures show the western preponderance of the species better 

 than auy summary of the twenty-eight groups into which I have divided 

 the genus, which, besides being rather unequal in the number of con- 

 tained species, often show an extremely wide distribution or more than 

 one center of distribution, in the latter case indicating, perhaps, the 

 imperfection of the grouping. Still, leaving out the five groups, each 

 of which contains one or more transcontinental species, it will be noted 

 that there are three others which compass the continent the mancus 

 (five species), plebejus (five species), and robustus (five species) series. 

 Of the twenty remaining, one-half, viz, the flabellifer (six species), bow- 

 ditchi (six species), glaucipes (two species), utahensis (three species), 

 devastator (eight species), aridus (three species), rusticus (seven spe- 

 cies), borckii (six species), cinereus (six species), and packardii (five 

 species) series extend westward to the Pacific; while only five the 

 impudicus (one species), dawsoni (seven species), puer (two species), 

 inornatus (three species), and punctulatus (two species) series reach 

 eastward to the Atlantic coast; and the remaining five the lakinus 

 (three species), indigens (one species), alien! (two species \ augustipen- 

 nis (four species), and texanus (five species) series are found exclu- 

 sively, or almost exclusively, west of the Mississippi River. 



One-half of the series are represented in Mexico, showing rather 



'One species, M. lorealis, is reported, in lift., by Brunner to occur at Valdivia, 

 Chile; as its only other known localities are in the arctic regions, I am inclined 

 to doubt the correctness of the determination, and presume the material to be 

 insufficient. 



