Nov., 1902.] 
Passalus Cornvlus. 
3 1 1 
bar and to unite in the middle line in a slight elevation between 
the inner ends of the coxa. It is separated on the median line 
from the second sternum by a decided notch. The second sternum 
is indented by the coxa and presents a median elevation between 
the coxae which is visible on the surface. The median elevation 
on the first segment cannot be seen from the surface. The second 
and third sterna articulate; the remainder are imovably fused. 
The third, fourth, fifth and sixth sterna are fused and. like the 
first and second, are inflexed at the sides of the body and end in 
a well-defined suture just beyond the point of inflexion except 
the surface. The seventh sternum is not visible on the ventral 
surface of the body, but can be seen on the posterior end of the 
body forming the ventral wall of the anal opening. It is crescent- 
shaped and bears a number of short hairs. It cannot be divided 
into sternum and tergum. 
There are seven pleura corresponding to the seven sterna. 
The first six are distinctly separated from the sterna by a well 
defined longitudinal suture. The seventh is fused with its sternum 
to form the ventral wall of the anal opening. Each sternum is 
fused to its corresponding tergum. 
The abdominal spiracles are situated on the dorsal anterior 
borders of their respective pleura, excepting the second, which 
lies anterior to its pleuron and directly over the end of the large 
first abdominal spiracle. The first abdominal spiracle is the large 
one described in connection with the meta-thorax. The seventh 
spiracle is much reduced in size and difficult to see from the sur- 
face. 
There are seven abdominal terga ( 2 ’- 7 ’) corresponding to the 
seven pleura, but there are eight in all. The first is the broad 
membrane lying in contact with the metathoracic postscutellum. 
The second, third, fourth and fifth are similar and membranous. 
The sixth, seventh and eighth are chitinized more or less, and the 
seventh is called the propygidium. and the eighth the pygidium. 
The eighth forms the dorsal wall of the anal opening. 
