﻿March 1895.] LaNDER. DoMES OF CiCADA SEPTENDECIM. 31 



later appear. Exactly such a case — open burrows among the domes> 

 has been reported to me by a well known entomologist. 



A unique illustration of the protective function of the dome 

 is shown in a circumstance which occured during a former advent 

 of the Cicadas. A scientist and writer on entomology informs me 

 that some laborers in cutting through a bank laid open the burrow 

 of a pupa: Soon after, "upon the fresh, vertical cutting there 

 appeared one of these 'huts' rising from the opening". Here was 

 a shallow biirnnv (artificially <iO.) prematurely opened; \\\t. undeveloped 

 pupa erecting a shield against the vicicitudes of external temper- 

 ature ; which would also serve as a protection against outside 

 enemies : a perfectly logical analogism. 



Perhaps enough substantiating facts have been adduced, but 

 two features of the cases observed by me ar-e so significant that 

 they lend extreme probability to the explanation I offer, and cer- 

 tainly disprove the heredity theory. First: No open holes occured 

 in the areas over the smooth glacial-worn rocks — there the soil 

 was almost uniformally shallow; and it is beyond belief that what 

 few "low ground" builders in the past that might have stolen 

 horse-back rides to the mountain tops and the lofty Palisades, 

 should have chosen just such prescribed places, and have utterly 

 annihilated the open burrow builders — native to the soil. Second: 

 A wide and deep gully (of course subject to overflow,) in the area 

 of the largest Cicada city had no domed burrows, as there the 

 earth was deep, from the alluvial deposits of ages, but later, when 

 the great swarm arrived, this hollow was found to be honey-combed 

 with open holes. 



In conclusion, with reference to the causes and purposes of 

 the domes, in view of what has been adduced it seems altogether 

 likely that every one, no matter when or where observed, was 

 erected by an undeveloped pupa that had prematurely opened its 

 burrow from near the surface, and closed it as a protection while 

 awaiting maturity. 



Previous accounts erroniously state that these heretofore rare 

 objects have an orifice at the surface of the ground. When the 

 time for moulting arrives a hole is clawed through the roof (Fig. 

 3). A unique specimen in my collection shows the cast-off shell 

 of a pupa firmly fixed in the opening : the hole had been made too 

 small for entire emergence, but the little fellow had been able to 

 escape from his horny armor. Many specimens show clear im- 



