26 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
Laterals: one or more l)ristles on, or on and near the lateral margins 
of the segments (PI. 5, fig. 31, ht-L). 
If there is no distinct separation between the marginals and laterals, 
either by spacing or difference in size of the bristles, the segment is 
said to have a complete marginal row, but this refers only to the dorsal 
surface unless otherwise stated. 
Pkeparation of Specimens. 
The great majority of specimens die and are allowed to dry with 
the legs so drawn up that many important characters, not only of the 
legs themselves but also of the lower surface of the thorax and abdo- 
men, are obscured. To obviate this, the legs should be at least 
partially stretched out after death before the fly is allowed to stiffen. 
Especial care should be taken so to place the posterior legs that they 
do not conceal the ventral plates. 
Only rarely are specimens caught with the copulatory apparatus 
exposed, and if it is desired to study the genitalia it is necessary to 
pull the genital segments from their resting place. In order to do 
this, Bottcher recommends that the flies be left over night, as the 
elastic resistance which tends to cause the segments to spring back into 
their resting position will give way to a waxy flexibility. Old dry 
specimens he leaves in a moist chamber for twenty-four hours. To 
pull out the segments, the pinned specimen is placed obliquely on a 
"Torfplatte," the forceps clasped with " Splitterpinzette " and drawn 
outward and backward till the penis forms a right angle with the body 
axis. It may sometimes be necessary to raise the penis to its proper 
position as it does not always pull out of the pocket. 
In addition, I have found the following methods useful. Number 00 
steel pins are more convenient than forceps especially when handling 
small specimens. Freshly caught flies may be left over night as recom- 
mended above or if that is not expedient, the specimens may be stuck 
into the cover of a shallow pasteboard box, a slide box for example, 
the genital segments having been first loosened by inserting a pin in 
front of the forceps and exerting a backward pull. Another pin is 
now run up through the cover from beneath, extending obliquely 
upward and backward from near the insertion of the pin bearing the 
specimen. The point of this pin is pushed between the forceps at 
their base and the whole pushed upward and backward. If left thus 
for about twelve hours, the parts will have dried in place. 
