304 



NORTH AMERICAN DIPTERA 



As here understood this family comprises the genera Calohata, and 

 Cardiac cphala of the old family JMicropezidte. They really have little 

 in common with this latter group except a superficial resemblance. The 

 classification of the family is poor and several of the genera are based 

 upon what appear to l^e trivial characters. Several of the genera oc- 

 curring in South America, as w-ell as a few included in the following 

 key, are unknown to me so I am unable to do more than use the char- 

 acters cited by tlieir describers althougli I think that most of the genera 

 are well founded and could be readily recognized upon characters other 

 than those used. The genus Cardiacephala Schiner, of whicli I consider 

 both PlocosceJus Enderlein and Rhoecius Enderlein to be synonyms, 

 merely displays a diversity in head shape not found in other groups, 

 but no sharp lines can be drawn between the three proposed genera. 

 Some insects show specialization along one line, others in other w^ays. 



Calobatidae II. — 14, Hoplocheiloma; 15. Grallomya annulata; 16. Taeniaptera ; 17, Gralli 

 peza; 18, Rainieria; 19, Ptilosphen; 20, Calobata univittata; 21, Cardiacephala. 



