﻿OF THE STATE ENTO:^[OLOGIST. 



41 



/ \ 



[Fig. 13.1 



I'ropoda Americana: — a, Colorado Potato-beetle attacked by it — iiat. size; 

 b, the mite, veutral view, and showing the penetrating organs lying between the 

 legs; c, the organs extended; d the claw; e, the excremeutitious fllament— all 

 greatly enlarged. 



species has convinced me that the similar anal filament, which also 

 helps it to adhere to Doryphora, is in reality excrementitious, stick- 

 ing to the beetle and to the raite by a flattened disc at either end — 

 being quite fragile and easily broken. Tne true penetrating organs, 

 which enable the mite to hold tenaciously to its victim, and doubt- 

 less assist in obtaining nourishment, I have discovered to be a pair 

 of extensile processes, each armed at the tip with a bifid claw, some- 

 what resembling that of a lobster. When at rest these organs are 

 retracted and lie between the legs and just under the skin. When 

 extended, they are usually brought closely together and extend the 

 whole length of the animal beyond the head. They seem to be thrust 

 forward by a series of muscles at the base, and I have frequently seen 

 one extended while the other remained retracted. Thus, in addition 

 to the more frail excrementitious and adhesive filament, this Uropoda 

 is provided with an organ that is beautifully adapted to penetrating 

 the hard covering of beetles, and of thus securing it to its slippery 

 support.* 



* As will he seen by the figure, these organs in repose extend so far back toward the anus that it 

 is difficult to believe that they compose part of the mouth structure. Yet in carefully studying them I 

 felt convinced that they were maxillte, or rather the homologues of these organs in hexapods, and, in 

 June, 1876, so iuformeil Dr. A. .S . Packard, Jr. , to whom I submitted specimens Through his cour- 



length ami r<in>iderably in form in dift'erent species He considers them li-joiuted. ihe basal joint simply 

 cylindrical, till' Keccind "likewise so at base, but ending in a strongly chitinized claw, generally toothed 

 inside, anil tlie third lorming the inside linger of tlie claw, also generally toothed. In Uropoda vlineri- 

 cana no true joints are discernible in the body of the processes, though there tue restric'ions. These 

 maxilliB are evidently elastic and the anterior'portion may be retracted moreor less into the basal. Nor 

 should I designate as a joint the thumb-like articuhition of the terminal claw. Indeed, the.^e claws 

 seem to me to both of them articulate on the end of the process. In the species uuder consideration 

 (wo teeth aro sometimes discerned on the small thumb, but ordinarily they are not easily resolved. 



