Nov., 1902,] Passalus Cornulus. 311 



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'-'/') 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. 



