THE OLFACTORY SENSE OF ORTHOPTERA 

 MORPHOLOGY OF THE OLFACTORY PORES 



407 



Before making a study of the anatomy of the olfactory pores, 

 the distribution and number of them were first investigated. 



Disposition of pores in a grasshopper 



From the eggs of Melanoplus femur-rubrum DeG., all six in- 

 stars were reared, and since the fifth instar was most favorable 

 in size and in condition of the integument for a critical study, the 



Figs. 1 and 2 Disposition of olfactory pores on the first and second antenna! 

 segments of female grasshopper (Melanoplus femur-rubrum, no. 18 in table 1) 

 in fifth instar. Fig. 1, dorsal surface, and fig. 2, ventral surface of same segments; 

 the inner edges of the antenna face one another. X53. 



pores on a female of this stage were studied and drawn in detail 

 as follows. 



a. Pores on head. Pores were found on the head capsule and 

 on all of the head appendages; on the former 7 scattered pores 

 were observed, but on the head appendages they are more or 

 less constant in position. 



The first antennal segment bears 4 scattered pores, 2 being on 

 the dorsal side and 2 on the ventral side (figs. 1 and 2, a-d) ; the 

 second antennal segment bears 2 isolated pores (e and/), besides 

 a group of 43 (g and h) which completely encircles the extreme 

 distal end of the segment. 



THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 31. NO. 5 



