124 MANUAL OF ANIMAL BIOLOGY 



The body of a Bee, consisting of the head, thorax, and ab- 

 domen, is entirely enclosed by the cuticula which is formed as a 

 secretion by a layer of cells lying just underneath. This chitinous 

 layer is quite rigid and affords protection and support for the 

 enclosed living tissues of the animal. It is comparable to the 

 exoskeleton of the Crayfish and Grasshopper. 



The external structure of the worker is somewhat different from 

 that found in either the drone or the queen. The body of the 

 drone is noticeably larger than that of the worker, and has a 

 broad, heavy abdomen which lacks a sting. The eyes are very 

 large. The body of the queen resembles that of the worker in 

 general contour, but it is larger and the abdomen is more elongated. 

 The metathoracic legs of the queen and drone are also slightly 

 modified. We may now consider in detail the various structural 

 features as found in the worker. (W. fs. 214, 216.) 



1. Head 



It is generally believed that the head of the Bee is composed 

 of six segments. However, the segmentation even in the em- 

 bryonic condition is not entirely clear and, in the adult, segmental 

 lines are not present. Attached to the head are several highly 

 specialized structures and appendages which may be summarized 

 as follows (W. f. 215) : 



(a) A pair of large compound eyes which protrude from either 

 side of the head. These are essentially similar in structure to those 

 noted in the Grasshopper. Three other tiny, simple eyes (ocelli) 

 are situated near the median line of the 'forehead.' 



(b) A pair of antennae which are attached to the anterior 

 surface of the head and project forward and ventrally. They are 

 jointed structures which serve as very important sense organs. 



(c) A dome-shaped portion, the clypeus, of the anterior wall of 

 the head, which lies just below the points of attachment of the 

 antennae. The upper lip, or labrum, is attached to the lower 

 edge of the clypeus. 



(d) Below the labrum is an unpaired, fleshy structure, the 

 epipharynx, which is apparently an organ of taste. 



(e) A pair of jaws, the mandibles, which are attached, one at 

 either end of the labrum. The mouth opens between the mandi- 

 bles. When closed, the mandibles lie over the labrum and epi- 

 pharynx so that these structures cannot be seen when the head is 



