102 



speed. These observations rectify, in many important partic- 

 ulars, the statements of Newport, based of course on an* exam- 

 ination of alcohohc specimens. Dr. Hagen noticed, moreover, 

 a remarkable degree of individual vai'iation in these insects, 

 especially in the form of the head and prothorax and in the 

 female organs of generation. 



During the summer of 1876, Rev. Henry C. McCook stud- 

 ied the habits and architecture of the wood-ant (^Formica ruf a) , 

 whose mounds are abundant in the mountains of Pennsylvania ; 

 and has just given a very interesting account of his observa- 

 tions. He camped for a week in the immediate vicinity of a 

 large colony of nearly seventeen hundred hills, covering an 

 area of twenty hectars. Although Huber, Forel, and others 

 have already given long accounts of the habits and architect- 

 ural skill of this ant, the independent testimony of an observer 

 on this side of the Atlantic has a peculiar value, and appears at 

 first sight to indicate some diversity in the habits of this species 

 on the two continents. I am not aware whether any differ- 

 ences betAveen the ants themselves have been observed ; but as 

 differences, at least varietal, do occur in American and Euro- 

 pean examples of Formica sanguinea and Lasius flavus, two 

 other common ants found in both countries, the distinction of 

 habits found by Mr. McCook in Formica 7'ufa has an impor- 

 tant bearino;. 



The mounds made by these ants are cones of greater or less 

 regularity, generally three or four metres in circumference at 

 the base, and seven and a half to nine decimetres high ; one 

 double hill — the blending of two hills — was found measuring 

 more than seventeen and a half metres in circumference, and 

 considerably more than a metre in height. Not only do the 

 hills appear to be grouped in large colonies, but each colony is 

 made up of family clusters, probably the work of a single 

 republic. The hills are mostly composed of earth brought 

 from beneath, but the surface is strewn, to a greater or less 

 extent, with bits of decayed wood, pine needles and fragments 

 of straw, though apparently not to the extent that is described 

 in the nests of the European ant. This surface material is 

 brought in by surface foraging. The nest is honeycombed 



