OF WASHINGTON, VOLUME XIII, 1911. 153 



represent the tachinine type or group-unit. Chcetotachina has 

 the spermathecal duct extremely elongated and longer than 

 the tubular glands, the latter being not only much shortened 

 comparatively, but also very slender, much more slender than 

 the spermathecal duct; moreover, there is only one sper- 

 matheca, according to Pantel, which seems to me most re- 

 markable, since in all of my work I have never found any 

 variation from three. Thus the chaetotachinine group is a 

 most distinct one. 



The bulb-like enlargement in the spermathecal duct of 

 Chcetotachina noted and figured by Pantel is considered by 

 him as perhaps a supplementary spermatic reservoir. This 

 might well be the case in this form with only one spermatheca, 

 but I find the same well developed in Enphorocera peruviana 

 and E. minor, two Peruvian species, both of which have 

 three spermathecae. I think it more probable that these 

 bulb like swellings of the ducts function alternately as air- 

 exhausts for drawing the spermatozoa down from the sper- 

 mathecae through the very long ducts and as expellers for 

 forcing them into the uterovagina. They are very marked and 

 quite spherical in the Peruvian species mentioned, and strike 

 me as being especially comparable to the bulb of a syringe. 

 They may also function as spermatozoal inhibitors during 

 copulation. 



Of the forms above mentioned, so far as known, only Mei- 

 genia and Thrixion have a uterus in my sense, which is 

 termed by Pantel "uterus incubateur" and "organe incuba- 

 teur", and by Uufour ''reservoir ovo-larvigere. " Pantel con- 

 siders the uterus present in all forms; I consider it present 

 only in those forms which incubate the eggs. The cor- 

 responding organ in those forms which do not incubate the 

 eggs I call the uterovagina, which has no incubating but only 

 a fertilizing combined with a vaginal function; it thus can not 

 properly be called either vagina or uterus, since it combines 

 the functions of the two. The vagina is the more or less 

 well-marked termination of the incubating tube or sac; thus 

 the uterus plus the vagina in the incubating class are homol- 

 ogous with the uterovagina of the non-incubating class. 



Pantel records his belief that incubation of the eggs in 

 Meigenia and Thrixion is probably to be considered excep- 

 tional. I can hardly agree to this. I have found eggs in a 

 number of these forms sufficiently developed to show the 

 cephalopharyngeal skeleton of the maggot, and further the 

 elongate coiled uterus would not be present, I believe, unless 

 for the purpose of incubation. Similar incubation is known 



