13° 



THE STUDY OF INSECTS 



The openings in the thoracic segments in which the legs are inserted 

 are termed the coxal cavities. Much use is made in the classification of 



Fig. 216. — Prothorax of IJarpalus, ven- 

 tral aspect: c, coxa; em, epimerum; es, 

 episternum; /, femur; n, pronotum; s, s, 

 s, prosternum. 



Fig. 217. — Prothorax of Pentlie; c, 

 coxa; cc, coxal cavity; /, femur; s, pros- 

 ternum; tr, trochanter. 



beetles of the form of the coxal cavities of the prothorax. When the 

 epimera of the prothorax extend behind the coxae and reach the pros- 

 ternum, the coxal cavities are said to be closed (Fig. 216); when the 

 epimera do not extend behind the coxae to the prosternum, the coxal 

 cavities are described as open (Fig. 217). 



The tarsi of certain beetles. — In the suborder, Polyphaga, there is a 

 group of beetles, the Phytophaga, in which the tarsi appear to be four- 

 segmented. The fourth segment is a very small one situated deep in be- 

 tween the lobes of the third segment and is firmly united with the fifth 

 segment (Fig. 218, A). Other types of tarsi in the series Palpicornia, Poly- 

 formia, and Clavicornia are shown in Figure 218. 



Fig. 218. — Tarsi of beetles: A. PhytophaRa; B, C, 

 D, of the series Palpicornia, Polyformia, and Clavicornia. 



TABLES FOR DETERMINING THE FAMILIES OF THE 



COLEOPTERA DISCUSSED IN THIS MANUAL 



TABLE I. — THE SUBORDERS 



A. Ventral part of the first segment of the abdomen divided by the hind coxal 

 cavities, so that the sides are separated from the very small medial part. Suture 



