PARKER: NHW KNCJLAXD SARCOPHAGIDAE. 33 
then 1k> gciu'ric-. Indctd, the li\ potlictical coiiclusioii must \h\ that 
sometime Surcophiifja, tis a genus, will hnNe disappeared, hut will he 
represented l)y derived jjenera, defined in several different, hut inter- 
locking sets of the specific characters of Sarcophaga. 
Of interest along this line of argument is Coquillett's genus Heli- 
cohia foiuided on a species, SarroplKU/a lirlicis, descrihed hy Towiisenrl. 
iVIost certainly the generic characters given were those of specific 
value in Sarcophaga, hut the right combination of these characters, 
if such exists, was not gi\cn. The fact that I)f)th the first and the 
third veins are bristly seems to have been the principal character indi- 
cated, — at any rate Coquillett afterwards placed Ravinia quadrisetosa 
in that same genus, whereas, to my mind, the relationship between 
these two species is distant at best. Quadrisetosa certainly belongs 
to Ravinia and helicis probably to Sarcophaga, as far as can be deter- 
mined at present. 
In respect to Ravinia and Boettchcria as derivations from Sarco- 
phaga, this fact is also patent: that while the genital dissimilarities repre- 
sentative of species are, as a rule, most marked in that genus, they are 
far less so in the other two. Not in all cases, but in many, their species 
are much more expeditiously identified by external characters than by 
those offereVl by the penes. Considering the characters of the male 
organ of generation as the most conservative, the external characters 
being more adaptive, this is only the logical result. Boettcheria and 
Ravinia as comparatively new genera, might well tend to show external 
specific modification much quicker than others of similar value on the 
penes and its associated structures. These would in many cases be 
adaptive characters, but it is doubtful if the entomologist can escape 
the use of these as specific characters. Following the generic descrip- 
tion of Boettcheria are listed characters which may possibly be generic, 
possibly specific. They are characters which, while not of specific 
value in any case studied, yet show differences of degree. For this 
reason in both this genus and Ravinia a certain repetition of like char- 
acters occurs in the descriptions of the species. 
For most species within these genera (there are possible exceptions 
not as yet sufficiently studied to make a positive statement) the penes 
may probably be safely taken as the criterion of species. Sul)species 
may then be made on characters of the fourth ventral plate and 
forceps, sometimes on external characters though certainly not by one 
unfamiliar with the tendencies toward variation exhibited by the 
