250 THE CANADIAN ENTOMOLOGIST. 



create a new genus tor Horn, expansa, Lee, and I fully agree with Mr. 

 Casey on this point. 



(c) Soliusa cannot be divided generically from Homceusa. 



(d) Myrmobiota cannot be divided generically from Homceusa. 



{ad c) The only important differences between Soliusa and Homceusa 

 are : The two basal tergites narrowly and deeply impressed in Homceusa, 

 not impressed in Soliusa; the basal joint of the posterior tarsi nearly (or 

 fully) as long as the next two combined in Homceusa, distinctly shorter 

 than the next two combined in Soliusa. The first difference is no generic 

 one, but only a specific one ; the second is sometimes a generic, some- 

 times only a specific difference [<?. g., in Lomechusa mougolica, Wasm., the 

 first joint of the posterior tarsi is nearly twice as long as the second and 

 twice as broad; in Lomeclmsa strumosa, ¥., it is only very little longer 

 and scarcely broader than the second ; similar differences exist also 

 between Atemclcs pubicollis and paradoxus, and between Myrmcecia 

 ( Nototaphra) laida and lugubris, Cas.]. If no other important differ- 

 ences join themselves to this one, it cannot be regarded as a generic, but 

 only as a specific, difference. 



(ad d) The only important differences between Myrmobiota and 

 Homceusa are the thickness of the antennae, the form of the thorax, and 

 the relative length of the basal joint of the posterior tarsi, the latter 

 difference being the same as between Soliusa and Homceusa. I refer to 

 the above exposition. As to the thickness of the antennae in Myrmobiota, 

 this character may be only of specific value, if no other important differ- 

 ences are joined to it (cf. the different specific thickness of antennae in the 

 genus Myrmedonia, Er., or in the genus Philusina, Wasm.). As to the 

 different form of the thorax, its sides being nearly parallel towards the 

 base and with rectangular basal angles in Homceusa, evidently contracted 

 towards the base with obtuse basal angles in Myrmobiota, the posterior 

 margin being distinctly sinuated in Homceusa, not visibly sinuated 

 in Myrmobiota, this difference could be a generic one if it were connected 

 with other important differences ; but it can be also merely a specific 

 difference. This seems to be confirmed by the fact that the sides of the 

 thorax are distinctly converging towards the base in some of my 

 specimens of Homceusa acuminata, parallel in others. We must not 

 forget that the form of the thorax is often widely different in different 

 species of the same genus of myrmecophilous Aleocharini ; cf. Atemeles 

 emarginatus, Fayk., and paradoxus, Grav.; Lomechusa strumosa, F., and 



