1 1 8 Invertebrata. 



pair are named mandibles or biting jaws, the lower pair 

 maxillae or chewing jaws. The last-named have usually 

 appended to them on each side a pair of small 

 jointed feelers or maxillary palps. In the bluebottle 

 and house-fly the lower lip is lengthened into an elon- 

 gated gutter-like sheath in which are contained the 

 maxillae and mandibles, which are reduced to mere 

 bristle-like processes. 



In the bee (fig. 77, p. 132) the upper lip and 

 mandible are strong and fitted for chewing, while 

 FIG. 6 7 . tne rnaxillae and lower lip are long 



and channelled, so that when 

 placed in apposition they make 

 a tube through which the insect 

 sucks in honey. In these crea- 

 tures the lower lip consists of 

 two parts, an upper or tongue 

 and a hinder part or mentum. 

 In the butterfly, the mouth has 

 lost all trace of its chewing func- 

 tion and the maxillae form two 

 half tubes, and when opposed as 



Head and proboscis of But- , . . , 



terfly, showing antennae they always are they make up a 

 canal, and being very long and 

 curved, this is sometimes called the proboscis. Each 

 of these maxillae has within it also a fine tube, and thus 

 a transverse section through the proboscis shows three 

 tubes, one medial between the maxillae and one lateral 

 on each side within each maxilla. Behind this proboscis 

 lies the labium, which has usually large palps between 

 which the proboscis lies when retracted ; for, unlike 

 the tube in the bee, this proboscis is freely retractile. 



