170 THE CANADIAN ENTOMOLOGIST. 



ON THE DISTRIBUTION OF THE GENERA OF CARABID^ 



ALONG A RIVER SYSTEM. 



BY C. H. T. TOWNSEND, CONSTANTINE, MICH. 



The St. Joseph River runs nearly diagonally through the township of 

 Constantine, from N. E. to S. W. A small affluent, called Fawn River, 

 empties into it at the point where the town itself is located. 



The characteristic vegetation along the banks of the main river above 

 town is beech, maple, elm, iron-wood, walnut, butternut, papaw, magnolia 

 (or a tree very nearly allied), spice-bush, prickly-ash, sumach, witch-hazel, 

 wild grape, ash, oak and hickory, with many quite rare and beautiful wild 

 flowers, such as are found in rich and favorable places. But that of the 

 affluent region is almost entirely oak and hickory (mostly oak), with hazel, 

 sumach, a few poplars, willows, and in some places cedars, but with few wild 

 flowers of any account. The cedars are also found upon the main river, 

 both above and below town. This difference in vegetation is probably 

 due to a difference in the nature of the soil, the lower and richer soil of 

 parts of the main river producing a richer and more varied flora than the 

 higher and poorer parts adjoining the affluent. 



Now I have noticed in collecting that the Carabidce seem to be dis- 

 tributed in a somewhat systematic manner along the main river and its 

 affluent, genera occurring on the former which are not found along the 

 latter, and less frequently vice versa. On the main river I have taken 

 Omophron, Helluomorpha, Galerita, Brachylobus (Lithophilus [Say] ), 

 DicaduSt Hcstonotus and Amphasia, which I have not taken on the 

 affluent. Galerita, however, I have taken on the prairie to the south, but 

 this partakes more of the nature of the main river region. 



While on the affluent I have taken Notiophihis, Calosovia and Pasim- 

 achus, which I have not taken on the main river. The Notiophilus is a 

 specimen which I have determined to be sibiricus Mots. It was taken on 

 19th October, 1884, while I was chopping over some sod with a hatchet 

 on an elevated grassy bank, which formed an open spot in the woods at 

 this place. As this is the only specimen of the genus I have up to this 

 time met with here, it may be found yet upon the main river. Of Cal- 

 osoma, I have often taken calidum (Fab.), and once scrutator (Fab.), 

 up the affluent. The latter, a very rare insect here, three or four speci- 

 mens only having been taken to my knowledge within the last 



