OLFACTORY ORGANS OF. A COLEOPTEROUS LARVA 123 



of AUorhina no groups are present, and the single olfactory organs 

 exist only as widely separated pores; nevertheless they are fairly 

 constant in number and in position. 



For description of the olfactory organs, the legs may be divided 

 into inner and outer surfaces, and the other appendages into 

 dorsal and ventral surfaces. The inner surface of the legs faces 

 the body of the larva and the outer surface is di.-'ected from the 

 body. Reference to figures 26 to 29 shows the disposition of the 

 olfactory pores on one of the three specimens examined; the 

 distribution of these organs on the other two specimens is prac- 

 tically the same, but the number of them varies slightly. 



Each hypopleural region (fig. 26, HR) usually bears at least a 

 few olfactory pores on its outer surface; these are generally near 

 the articulation of the coxa, but sometimes one or two may be 

 found near a spiracle which is a considerable distance from the 

 base of the leg. Considering the three specimens examined, the 

 pores on this part of the body vary from to 12, with 6 as an 

 average. Other parts of the body were examined, but no pores 

 were found on them. 



Each segment of the legs (figs. 26 and 27), except the tarsus, 

 always bears at least a few olfactory pores, and the tarsus^ usually 

 bears one or two. Considering the three specimens examined, the 

 number of pores on a coxa varies from 9 to 26, with 13 as an aver- 

 age; on a trochanter from 7 to 14, with 11 as an average; on a 

 femur from 5 to 11, with 8 as an average; on a tibia from 4 to 10, 

 with 7 as an average; on a tarsus from 1 to 2, with almost 1 as ah 

 average. As an average for the three specimens examined, the 

 outer surface of all six legs bears 132 pores and the inner surface 

 102 pores, making 234 pores as an average for all six legs. 



Each segment of the head appendages, and even the head 

 proper, invariably bears at least a few olfactory pores, which are 

 widely distributed as may be seen by referring to figures 28 and 

 29. Considering the three specimens examined, the number of 

 pores on an antenna varies from 45 to 53, with 50 as an average; 

 on a mandible from 2 to 8, with 5 as an average; on a maxillary 

 palpus from 17 to 23, with 18 as an average; on a lacinia from 27 

 to 45, with 35 as an average; on a cardo from 10 to 15, with 12 



