1-56 EXTERNAL ANATOMY OF INSECTS. 



inner piece has on each side a roundish space, attached 

 to the under surface of the t\vo sides of the rhinarium, 

 beset also with bristle-bearing tubercles. You will find 

 something similar lining the labrum and nasus of some 

 Coleoptera, — say Geotrupes, Necrophorus, and Dytiscus. 

 The first piece I regard as the analogue of the palate, and 

 the second as connected with the sense of smelling. In 

 Necrophorus the circular pieces are covered with a finely 

 striated membrane, and in Dytiscus each has a little 

 nipple. 



8. Pharynx a . — On the upper side of the tongue, usu- 

 ally at its base or root, is the pharynx, or aperture by 

 which the food passes from the mouth to the oesophagus. 

 This orifice, which is situated with respect to the tongue 

 of the Orthoptera and Libellulina nearly as in those in- 

 sects (at least as far as I have been able to examine them), 

 whose tongue is called a ligula or labium, — of course ex- 

 ists in all the mandibulate Orders whose mouth we are 

 now considering. In the Hymenoptera it is covered by a 

 valve, the Epipharynx of Savigny; and it appeared to me 

 to be so likewise in one of the Harpalidce that I examined. 

 The formation seems different in Geotrupes, as far as I 

 can set an idea of it: but it is so difficult to examine the 

 interior of the mouth without laceration of some of the 

 parts, that I can only tell you what the appearances were 

 in one instance, upon removing the labrum from the man- 

 dibles; and in another, separating the whole apparatus 

 of the labium, including the maxilla:, from the mandibles 

 and labrum. In the former case, the mandibles coincided 



il Plate VII. Fig. 14. f, 



