THE OLFACTORY SENSE OF ORTHOPTERA 411 



pseudospine on the tibia (fig. 15, e) usually bears 1 pore, but occa- 

 sionally 2 pores, and the base of each spine (fig. 14, k) always 

 bears 1 pore. The following pairs of pores are always constant 

 in position: 1 pair on each tibia (figs. 10, 13 and 15, d); 1 pair on 

 the first tarsal segment (figs. 10 and 13, g) of the front and middle 

 legs and 2 pairs on the same segment of the hind leg (figs. 14 and 

 15, g and I) ; 2 pairs on the third tarsal segment (figs. 10 to 15, 

 h and m) of each leg, and 2 pairs on the dorsal surface of each 

 claw and pulvillus (fig. 15, i and j). 



The other isolated pores are represented in the figures by dots 

 (fig. 15, a, b, and c); these are very variable in disposition and 

 are much smaller than the other ones. All parts of the thoracic 



Figs. 16 to 19 Disposition of olfactory pores on wings of same grasshopper 

 as mentioned in figures 1 and 2. Fig. 16, dorsal surface, and fig. 17, ventral sur- 

 face of front wing; fig. 18, dorsal surface, and fig. 19, ventral surface of hind wing. 

 X6. 



segments were not critically examined, but 39 minute pores 

 (fig. 15, a) were counted on fragments of these segments. 



Groups nos. 11 and 12 lie on the dorsal surface of the front 

 and hind wing (figs. 16 and 18) ; no. 11 consisting of 15 pores and 

 no. 12 of 19 pores. Several scattered pores are also present on 

 both surfaces of each wing (figs. 16 to 19). 



c. Pores on abdomen. In all, 45 pores were found on the ab- 

 dominal segments. Roughly speaking, most of these lie in four 

 rows extending the full length of the abdomen ; two of these rows 

 lie on the tergum and two on the sternum, the latter two near the 

 midline, but the former two far from the midline. Each segment 

 usually has at least 2 large pores and one or more minute ones, 

 which may or may not be in the rows just mentioned. The ovi- 

 positor bears 53 scattered pores. 



