158 GRASSHOPPER PARASITE. 



microscope, the stride running in a waving transverse direction. The 

 mouth-organs appear to be reduced to their minimum of development. 

 The only part visible, externally, is a minute papilla, on each side of 

 which are two bristles, the inner of which is stouter, tapering to an 

 acute point, and curved inwards, or towards its fellow of the opposite 

 side. They differ from the majority of acarides in having but six legs, 

 and these, being of but little use in so stationary a creature, are short 

 aud slender, projecting but little beyond the outline of the body. 

 They are six-jointed, garnished with short stiff bristles, and terminate 

 in two slender curved hooks. The anterior and middle legs are closely 

 approximate and situated near the anterior extremity of the body ; the 

 posterior are set a little nearer to each other, and a little in advance of 

 the middle of the body, being inserted at the posterior part of the ante- 

 rior division or lobe. Four hairs project from the posterior extremity 

 of the body. 



These parasites are found on the under side of the basal half of the 

 inferior or true wings, and adhere with such tenacity that it is difficult 

 to scrape them off with the point of a penknife. They appear to adhere 

 by their mouths and not by their claws. 



The acari of this country have been but little studied, and scarcely 

 anything has been done in the way of classifying them, or reducing 

 them to their proper genera. The present species appears to belong to 

 the division of Tromhidia hexapoda, of Hermann, and to the genus 

 Atoma^^ of Latrielle, chiefly characterized by the imperfect develop- 

 ment of the oral organs. 



The species of grasshopper which these parasites were found infest- 

 ing at Mr. Galubha's, was the common red-legged grasshopper {Calop- 

 tenus femur-rubrum, of De Geer). They are stated in the American 

 Entomologist to have been also found on the allied species so destruc- 

 tive west of the Mississippi river, and called by Prof. Uhler and Mr. 

 Walsh, the Caloptenus spretiis. The grasshopper upon which I found 

 them 80 numerous, in my own neighborhood, was also a common but 

 much larger species, the specific name of which I neglected to deter- 

 mine. It is probable, therefore, that they will be found infesting many 

 different species of grasshoppers, and I have accordingly appropriated 

 to them the specific name gryllaria^ indicative of this tribe of insects. 



* This is the generic term applied to these mites in the " Kegne Animal." The word 

 Astoma, meaning moulhless, would have been more characteristic, and might be supposed to 

 have been the word intended, were it not that this latter term is appropriated, in the same 

 work, to a genus of radiate animals in the class Acalepha, 



