68 THE PERIODICAL CICADA. 
writes as follows: "They are found in both wet aud dry places; on the 
low and on the high ground; singly and in colonies of many thousands. 
One hut, even in a damp soil, may be surrounded by a dozen holes, 
from which the insects emerge without making any huts, and often 
where we may expect to find them they are never seen." Accepting 
the theory proposed by Mr. Lander for the condition found to exist in 
the ^yack region, Dr. Love does not deem it entirely adequate, as he 
says: "The huts are sometimes found in places in which the soil is of 
great depth and which are not especially exposed. Sach was the case 
at Baychester, where only a few huts were found, and these in deep 
soil aud so well protected that it was only after careful search that they 
were discovered," He offers the supplementary explanation that since 
it is hardly possible that the Cicada larva can determine instinctively 
the distance to be traveled in their upward journey nor the time 
required to accomplish it, which will vary with the nature of the soil 
to be tunneled and the directness of the line followed in their excava- 
tions, it may often happen that individuals reach the surface before 
they are prepared to assume the adult condition, aud the number so 
doing would be greater when the conditions all uuited to favor a short 
passage. In protected localities where the soil is deep the larvas lying 
near the surface will be more likely to emerge before their pupal changes 
are complete, and would thus be led to the construction of these cones. 
This, he says, would also explain their seeking temporary shelter, as 
they do, under logs and stones, as has been previously noted. 
The explanation offered for the construction of the Cicada cones by 
Mr. Lander, as supplemented by Dr. Love, seems, .on the whole, satis- 
factory and adequate, so far as the conditions studied by these writers 
are concerned. The conditions as described by Mr. Rath von do not 
inform us as to the nature of the soil, but both in the Eathvon case 
and the later instance described by Mr. Davis, the wet character of 
the ground would seem to indicate a soil of a considerable depth. 
This would seem to give a basis of reason for the explanation suggested 
by Mr. Eathvon and accepted by Professor Eiley. A complete hypoth- 
esis, therefore, seems to be in a union of the explanations offered, 
namely, that the cone-building habit is induced either by a shallow 
soil, proximity of the pupae to the surface, or conditions of unusual 
warmth, which brings the pupae to the surface in advance of their 
normal time, and more rarely to unfavorable conditions of excessive 
moisture. 
The explanation of the occurrence of these structures on high ground 
suggested by Professor Eiley is certainly untenable. He surmised 
that the individuals constructing cones in such situations did so 
because impelled by habit that had become fixed and hereditary in the 
course of a long period of existence in low wet situations. The strict 
limitation of these cones to areas presenting peculiar conditions 
thoroughly disproved this theory. 
