THE EXTERNAL ANATOMY OF INSECTS 



45 



Fig- 57- — Maxilla oiCicindela. 



The galea or helmet (/) is the second in prominence of the appendages 



of the maxilla. It consists of one or two segments, and is joined to the maxilla 



^ mesad of the palpus. The galea varies greatly 



in form: it is often more or less flattened, with 



the distal segment concave, and overlapping 



the lacinia like a hood. It was this form that 



suggested the name galea or helmet. In other 



^-A>'*SJ ' \ 4 r^ t^^"^ cases the galea resembles a palpus in form (Fig. 



rX- \ \ \ V* r^~^ 57)- The galea is also known as the otiter lobe, 



'~'~^S\x^ ^^^"Z^ the upper lobe, or the superior lobe. 



The lacinia or blade (g) is borne on the mesal 

 (inner) margin of the subgalea. It is the cutting 

 or chewing part of the maxilla, and is often 

 furnished with teeth and spines. The lacinia is 

 also known as the inner lobe, or the inferior lobe. 



The digitus or finger {h) is a small appendage 

 sometimes borne by the lacinia at its distal end. 

 In the Cicindelidas it is in the form of an articu- 

 lated claw (Fig. 57) ; but in certain other beetles 

 it is more obviously one of the segments of the 

 maxilla (Figs. 55 and 56). 



The labium or second maxillce. — The labium or under lip (Fig. 53), 

 is attached to the cephaHc border of the gula, and is the most ventral 

 of the mouth-parts. It appears to be a single organ, although some- 

 times cleft at its distal extremity; it is, however, composed of a pair 

 of appendages grown together on the middle line of the body. In the 

 Crustacea the parts corresponding to the labiimi of insects consists of 

 two distinct organs, 

 resembling the 

 maxillae; and in the 

 embryos of insects 

 the labium arises as 

 a pair of append- 

 ages. 



In naming the parts 

 of the labium, entomo- 

 logists have usually 

 taken some form of it 

 in which the two parts 

 are completely grown 

 together, that is, one 

 which is not cleft on 

 the middle line (Fig. 



58). I will first describe such a labium, and later one 

 into two parts is carried as far as we find it in insects. 



Fig. 58. — Labium of Harpalus. 



in which the division 





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