PHYSIOLOGICAL ANIMAL GEOGRAPHY 567 
made in the other soils, together with the number of larvae which 
appeared; 80 per cent on the steep slope, 98 per cent in clay. 
The count of holes includes some in the first stages of digging, 
mere scratches on the ground, and others which had been exca- 
vated to the usual depth with or without eggs being laid. 
c. Factors controlling egg-laying. Pairs taken in coitus were 
placed in cages containing sand only and level clay only. No 
larvae appeared in either case. The experiment with the level 
clay has not been repeated. Females placed in cages containing 
rough, steep clay, deposited eggs. Eggs are also absent from dry 
soils, whether steep or level. 
Slope, kind of soil and soil moisture are factors governing the 
deficiency or absence of eggs. A deficiency or excess in any one 
of these respects decreases the number of eggs laid, or causes them 
not to be laid at all. The animals are in the condition for egg 
laying for a short period. 
d. Method of selection. It has been determined by opening 
holes that eggs are not laid in all, and in one case the first holes 
made by a female were empty. This would tend to show 
that they try the soil before laying the eggs, but I have not been 
able in other cases to determine whether the first holes contained 
eggs ur not. To determine this, it would be necessary to watch 
a female all of.the time during several days. 
5. Geographic distribution. a. Distribution of the species. 
This species occurs from the Island of Mount Desert on the coast 
of Maine, northward along the coast of Nova Scotia and New 
Brunswick, up the St. Lawrence River, through the region of the 
Great Lakes, and westward across the northern part of the great 
plains to Alberta, and south along the eastern slope of the moun- 
tains; southward in the upper Mississippi Valley to St. Louis. 
Its place in the great plains and southern prairie region is taken 
by other forms recognized as other color varieties, but so far as 
is known, similar in habits. These forms are the varieties or 
subspecies transversa, splendida, amoena, denverensis, and ludo- 
viciana. Splendida has recently been recorded by Sherman from 
western North Carolina. Occasional specimens are recorded from 
Kentucky, Tennessee, and northern New Jersey. It is evident, 
