2l8 



by incidental forms, such as the Carolina locust (Dissosteira Carolina?} 

 (40), with occasionally the red-legged locust (Melanoplus femur- 

 rubrum) and the two-lined locust (Melanoplus bivittatus). Under rock 

 fragments we took the ground beetle (Anisdactylus inter punctatus] and 

 the common cricket (Gryllus pennsyhanicus) . Hancock (40) states 

 that the smooth cockroach (Ischnoptera inaequalis Sauss) and the large 

 cockroach (7. major Sauss) occur in such situations. We found the nest 

 of a spider (Agelena naevia) attached to one of the loose rocks. 



Other stages have been studied only superficially. In the cracks 

 and crevices of rocks and rock piles, shrubs and vines grow and the 

 young forest, field, and shrub strata have all the appearance of the 

 shrub stage on clay at Glencoe. The animals are for the most part those 

 common to thickets. 



IV. FOREST COMMUNITIES ON SAND 



In chap, iii, pp. 46, 47, we discussed sand areas and their distribu- 

 tion. In chap, viii we noted the series of ponds and ridges with a little 

 regarding their origin (pp. 136-40). Their general relations are indicated 

 by Figs. 83, p. 137, and 84, p. 139. It appears that the margin of the lake 

 may, under conditions of rapid recession, become the margin of an inland 

 pond. Under condition of slower recession this belt may be buried and 

 hence come to lie beneath such belts as lie farther inland. Since the 

 sand areas about Chicago represent all the stages in the development 

 of forests, beginning with the bare sand and ending with the beech 

 forest, it is my purpose in the remainder of this chapter to follow the 

 animal associations and formations of forest development. Some of the 

 stages will be taken from till areas, but this is because these stages are 

 more extensive than the corresponding stages on the sand deposits. 



The chief stages are the wet sand of the water margin, the middle 

 beach, the cottonwoods, the old cottonwoods and pine seedlings, the 

 pines, the black oak, the black oak and white oak, the black oak-white 

 oak-red oak, the red oak-white oak-hickory, the basswood-red oak- 

 white oak-maple in moister places, and the beech and maple. 



I. THE WATER MARGIN ASSOCIATION 



(Stations 56, 58; Table XXXVIII) 



One morning early in June, we walked along the beach of Lake 

 Michigan for a mile and a half, for the particular purpose of studying 

 the animals of the zone within the reach of waves. Animals were few, 

 only stragglers of the regular residents which we have noted on p. 181. 



