72 



TEXT-BOOK OF ENTOMOLOGY 



Lbr 



mx. 



either mandibles or maxillae are present, its base may join them 



(Culex, female)." (p. 43.) 



We will now briefly describe the lingua, first of the mandibulate 



or biting insects, and then its specialized form, the hypopharynx of 



the haustellate and lapping insects. 



The lingua (hypopharynx) exists in 

 perhaps its most generalized condition 

 in the Thysanura (Fig. 69), where it 

 forms a soft projection, having the same 

 relations as in Anabrus and other Or- 

 thoptera. 1 



In the cockroach (Fig. 70), as stated 

 by Miall and Denny, the lingua is a 

 chitinous fold of the oral integument 

 situated in front of the labium, and ly- 

 ing in the cavity of the mouth. The 

 common duct of the salivary glands 

 enters the lingua, and opens on its 

 hinder surface. The lingua is supported 

 by a chitinous skeleton (Figs. 70, B ; 82, 

 shp). " The thin chitinous surface of the 

 lingua is hairy, like other parts of the 



mouth, and stiffened by special chitinous rods or bands." (Miall 



and Denny.) 



In the Acrydiidse (Melanoplus femur-mbrum) the tongue is a large, 



membranous, partly hollow 



expansion of the base of the 



labium. It may be exposed 



by depressing the end of the 



labium, when the opening of 



the salivary duct may be seen 



at the bottom or end of the 



space or gap between the 



hinder base of the tongue, FIG. 70. Hypopharynx of p t >r;/>!<i>,</,i 



, , . . . til/in- the arrow points out of the oppninjr of the 



and the inner anterior base OI salivary duct: A oritrin of salivary dud. li. side 

 ,i i i T , ,1 view. C, front view. After Miall and Dennv. 



the labium, as shown by the 



arrows in Fig. 70. It is somewhat pyriform, slightly keeled above, 

 and bearing fine stiff bristles, which, as they point more or less 

 inwards, probably aid in retaining the food within the month. The 



1 Uzel states that what is regarded as the ligula of Campodea is formed from the 

 sternite of the first maxillary segment ; while the two parts regarded as paraglossae 

 grow out from the sternite of the mandibular segment, and these three structures 

 together he regards as the hypopharynx. (Zool. Anzeiger, July 5, 1897, p. 234.) 



FIG. 69. Section of head of Ma- 

 chilis maritima : p', hypopharynx ; 

 Ibr, labrum ; t, tentorlum ; ph, room 

 in which the mandibles move on each 

 other ; />, paraglossa ; IMP , labium ; 

 sd, salivary duct ; s.ffl, salivary gland. 

 oe, wsophagus. After Oudemans. 



C 



