BRACHYGLUTINI 187 



Frontal extension in the form of a long, conical, subacute spine or 

 horn Group XV 



3. Pronotum with three subbasal foveae, a median and a lateral each side 4 

 Pronotum with a single subbasal fovea, the median 6 



4. Front more or less truncate ; epistome armed Group I 



Front more or less declivous ; epistome simple 5 



5. Anterior tibiae simple Group II 



Anterior tibiae dilated apically and ventrally sulcate Group III 



6. Base of pronotum with a row of small but sharply cut and well de- 



fined punctures Group V 



Base of pronotum lacking a row of punctures 7 



7. Antennae abnormal Group VI 



Antennae normal in both sexes 8 



8. All antennal segments much longer than wide Group XIII 



Antennal segments not all longer than wide 9 



9. Intermediate antennal segments cylindrical to obconic 10 



Intermediate antennal segments ovoidal, globular or moniliform 11 



10. Antennal segments III, IV, and V much longer than wide. . .Group X 

 Antennal segments III, IV, V, and VI much longer than wide 



Group XI 



11. Posterior tibiae strongly inflated; anterior and intermediate femora 



of males simple Group VII 



Posterior tibiae at most slightly thickened in apical half; inter- 

 mediate femora of males always inflated, excavated, and more or 

 less armed 12 



12. Intermediate antennal segments globular Group VIII 



Intermediate antennal segments ovoidal, a little longer than wide 



Group IX 



It will be noted that there are no neotropical species known at present 

 from Groups IV and XII of the genus. 



The above key follows Raffray (1904) in separating Decarthron into 

 fifteen groups of species. This is only a convenient way of separating the species, 

 without any necessarily implied evolutionary order. To my mind the separa- 

 tion of, for example, groups X and XI does not rank with the separation of 

 group XV. From the viewpoint of structural development it appears necessary 

 to divide the genus into two subgenera, Decarthron s.s. holding the first four- 

 teen Raffrayan groups, and a new subgenus Decarfuss holding the fifteenth 

 group. This latter group is very isolated, not only in the remarkable frontal 

 horn, but in swollen maxillary palpi, and is as unrelated to the general con- 

 cept of Decarthron as Drasinus or Euteleia. The fourteenth group, holding 

 Decarthron frontale Raffray alone, is not an annectant link between the rest 

 of the genus and the fifteenth group, viz: frontale is typical Decarthron s.s. 

 with excavated middle femora in the male sex, and the frontal prolongation 

 in this species is simply a quantitatively more pronounced development of 

 the front such as may seen in chichion at a much lower level of integration. 



