10 PSYCHE [February 
Another interesting feature in this Austro-transition area is the distribution of 
the three principal broods of the Periodical or Seyenteen-year Cicada (Tibicen 
septendecim). Whether the different geological formations have any bearing in the 
matter I cannot say. Brood XI (1920) which occurs only in New England, and 
which I am sorry to say has been almost exterminated, owing to the clearing of the 
woodlands, is (or was) confined chiefly to the Triassic area of the Connecticut 
Valley, with two small colonies in or near the Narragansett basin. Brood II (1911), 
distributed throughout eastern Pennsylvania, New Jersey and southern New York, is 
confined principally to the granitic area of western Connecticut. Brood XIV (1923) 
which is confined to the Tertiary of the Cape Cod region extending northward almost 
to the town of Plymouth, seems to have reached New England by way of Long Island. 
It is also interesting to note that of the five broods occurring in New England, no 
two broods occupy the same area, as sometimes occurs further south. 
On the coast of Maine there is an opposite condition to that of Massachusetts, 
the cold water and humidity presenting favorable conditions for many boreal trees 
and plants as far south as Mt. Desert and even to Casco Bay, which in turn foster 
many boreal insects. 
An important factor and one which enters into the distribution of insects, is 
the relation of the geological formation of the soil to plant distribution. ‘This is not 
as yet defined sufficiently to be of great value entomologically, but entomologists as 
well as botanists, should carefully consider this matter. In New England, even 
moderate elevations haye a more noticeable effect on vegetation than further south. 
In New Hampshire Prof. C. H. Hitchcock (Geol. N. H., Vol. I) states that chestnut 
and white oak follow quite closely the contour of 600 feet. His map illustrating this 
feature, shows a long narrow strip varying slightly in width, extending south from the 
White Mts. into Massachusetts. It is a gneissic or granitic area, forming the water 
shed dividing the tributaries of the Connecticut from those of the Merrimack river. 
The numerous peaks, some exceeding 2000 feet, and cold springs, the sources of the 
numerous streams, provide conditions governing the flora and insect fauna. ‘This 
upland area together with numerous local situations, such as cold swamps, constitutes 
the source of many boreal species that appear in what is considered the ‘Transitional 
zone. 
The relation of the flora to the abundance and distribution of insects, is not 
fully appreciated by the majority of entomologists. ‘The two are inseparable, and in 
preparing faunal lists a knowledge of the food plant and condition under which the 
larva exists goes far toward solying many problems. ‘The various oaks are preyed 
upon by a larger number of species of insects than perhaps all of the other hard- 
