OF WASHINGTON. 205 
and, blind and famished, the victim dies. In cases not fatal, after a month 
or two, these knots or warts drop off, leaving a scar resembling a burn. 
With very young chickens or puppies, death generally comes in the first 
stage, when every portion of their bodies is covered with innumerable 
enemies. 
Mr. Schwarz said that he had only met with the true flea and 
the Chigo {Rhynchoprion penetrans) in Florida, and that he is 
inclined to think that Judge Johnson is dealing with the latter. 
The specimens formerly sent by Judge Johnson were a true 
Pulex. 
Prof. Riley mentioned that the larvae of several mites produce 
an effect as described on chickens, but the true Chigo does not. 
Prof. Riley spoke on some " Microgasters affecting Rhopalo- 
cera." He called attention to the great variability of these spe- 
cies, and said that their specific distinction was more or less de- 
pendent upon individual opinion, and that this held in relation to 
the cocoons as weli as to the images. He stated that it was 
almost as easy to make a continuous series as to make well- 
marked divisions. He also said that M. pieridis Packard was 
the same as Apanteles glomerattts Linn., although the American 
form shows some slight differences from the European in the 
coloration of the legs. Extreme examples are easily separated, 
but there is a perfect series of intergrades. He could firtcl no 
entomophagic effects. Different hosts might make some differ- 
ence in the cocoons, but not in the imago. There were many 
excellent structural characters that could be used, as the sculpture 
on various parts, that of the scutellum being particularly valuable. 
Dr. Marx remarked that he was glad to find that others had 
found this difficulty in separating species. In spiders it was ex- 
ceptionally difficult, as there was much individual variation. 
There was always some slight difference between American and 
European spiders of the same species. 
Mr. Smith said that according to the Darwinian theory many 
of the structural characters must vary. In many groups he has 
had cause to doubt the existence of any species. Many times, 
however, the true characters have been overlooked, and closer 
study will bring out the species. He cited the genus Lachnos- 
terna, which he had recently worked out. He asked if the males 
of Microgaster had not some characters that could be utilized. 
