62 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 5 I 



Genus Cenosoma van der Wulp 



Ccnosoma signifera van der Wulp. — It is likely that this tropical 

 species will prove generically distinct from both Glstrophasia and 

 Buastrophasia, when sufficient material is studied. Two species are 

 probably confused in the catalogue under the name of signifera. 

 The Canadian and New England specimens are probably a northern 

 form distinct from the tropical one. CE. calva may be considered 

 congeneric with signifera. 



Subfamily Paramacronychiin.e 

 Genus Pachyophthalmus Brauer and von Bergenstamm 



Pachyophthalmus aurifrons Townsend.- — This species is quite 

 distinct from the European signatus Meigen, which probably does 

 not occur in America. It differs from signatus in the golden pol- 

 linose sides of front and face, third antennal joint about the length 

 of second, hind crossvein very slightly bowed, front quite strongly 

 produced, etc. P. signatus has pollen of front and face silvery 

 white with blackish reflections but without golden, third antennal 

 joint about twice as long as second, hind crossvein strongly bowed, 

 front scarcely protruded, etc. Both aurifrons Townsend and flori- 

 deusis Townsend are best assigned to this genus. 



Genus Sarcomacronychia Townsend 



Sarcomacf onychia unica Townsend. — This species, S. sarcopha- 

 goides, and S. trypoxylonis are to be considered as three valid 

 forms. The genus Pachyophthalmus differs from Sarcomacrony- 

 chia in having the ptilinal area wider in comparison with parafacials, 

 being three-fifths to almost three-fourths width of face ; cheeks as 

 wide as one-sixth to one-eighth eye height, or less ; eyes descending 

 but little lower than vibrissas, as seen in profile. Sarcomacronychia 

 has facial plate very small and restricted, being two-fifths to one- 

 third width of face, parafacials proportionately wider, often nearly 

 as wide as facial plate itself, but sometimes appearing narrow in 

 profile; width of cheeks from little less than one-fourth to about 

 one-fifth eye height ; eyes descending far below vibrissas, and even 

 below epistoma, nearly as low as lateral oral margins, as seen in 

 profile. Pachyophthalmus has the vibrissas inserted but little above 

 epistoma, and the antennae are inserted below middle of eyes. Sar- 

 comacronychia has vibrissa? inserted much farther above epistoma, 

 and the antennae are inserted on eve middle. 



