94 XOKTH AMERICAN MYRMECOPHILA (oRTHOPTERA) 



noted in the present ke.y to the species. The extremes of in(U- 

 vithial variation in each cause so close an approach to the normal 

 for the others, however, that these features are not as distinctive 

 as would be desired. 



Variation in General Size and in Form of Caudal Femora 



Individual size has provcMi an extremely interesting feature, 

 due to the fact that in all the species studied, not only is there a 

 direct influence generally exerted on the size of the individuals 

 of a colony by the size of their host ants, but also that in colonies 

 of very small ants, each species of these symbiotic crickets de- 

 velops a depauperate type, found under no other conditions, so 

 small that it would at first seem almost incredible so great a 

 reduction in the size could exist. A specimen of nebrascensis 

 repres(Miting this tjqie, 1.47 mm. in length, is the smallest adult 

 specimen of the Orthoptcra known to us. In o rcqoncnsis oXonQ is 

 the size influenced by geogi-aphic factors. 



The form of the caudal femora is found to vary in all of the 

 species. These members are ovate when short, thus of this type 

 in almost all of the smaller examples and normal in nebrascensis, 

 the smallest of the species studied. When the caudal femora are 

 longer, however, they assume a pyriform shape, this due to the 

 flattening of the dorsal margin. As a result, the species which 

 average larger, pergandei, oregonensis and manni, show more 

 frequently the ])> liform tyj^e. 



Life Histori/ 



The extremely intei-esting life histories of a mnnber of the 

 species of Myrmecophila already have been carefully studied. 

 As we have not had an opportunity for such observations, we 

 refer to the following important papers bearing on the subject. 



1819. Savi. Osservazioni sopra la Blatta acervorum di Panzer, 

 Gryllus myrmecophilus nobis. Biblio. ital., xv, pp. 217 to 219. 



1877. H. de Saussure. Melanges Orth., ii, pp. 457 to 461, 

 pi. 15 figs, xxvi, 1 to 5. 



1900. W. M. Wheeler. The Habits of ISIyrmecophila nebi-as- 

 censis Bruner. Psyche, ix, pp. Ill to 115, text figure. 



1901. Wasmann. Zur Lcbensweise der Ameisengryllen (Myr- 

 mecophila). Natur und ()fTenl)arung, xlvii, pp. 1 to 24. 



