308 PERIPATUS, MYRIOPODS, AND INSECTS. 



after the example of Marshall and Hurst. The entomologists divide 

 the protopodite into a lower joint the cardo, and an upper the stipes, the 

 endopodite into an internal lacinia, and an external galea, while the 

 exopodite is called the maxillary palp. 



(3.) The last pair of oral appendages or second maxilla are partially 

 fused, and form what is called the labium. The lower and upper joints 

 of their fused protopodites are called submentum and mentum ; the 

 endopodites on each side are double as in the first maxillae, and consist 

 of internal lacinia and external paraglossa ; the exopodites are called 

 the labial palps. 



The three pairs of thoracic legs consist of many joints, 

 are usually clawed and hairy at their tips, and vary greatly 

 according to their uses. Think, for instance, of the hairy 

 feet by aid of which the fly runs up the smooth window pane, 

 of the muscular limbs of grasshoppers, of the lank length of 

 those which characterise "daddy-long-legs," of the pollen 



FIG. 100. Joints of Cockroach's Leg. 



C, Coxa ; T, trochanter ; F, femur ; Tz, tibia ; Ta, tarsus with 

 terminal claws. 



baskets on bees, of the oars of water beetles. In identifying 

 insects from a book it is needful to recognise the joints of 

 the legs by the names which entomologists have transferred 

 to them from human osteology, viz., the superior coxa with 

 projecting trochanter, the stout femur, the tibia, and finally 

 numerous tarsal joints. 



Wings. 



Wings are flattened hollow sacs, which grow out from the 

 two posterior segments of the thorax. They are moved by 

 muscles, and traversed by "veins" or " nervures," which 

 include air-tubes, nerves, and vessel-like continuations of 

 the body cavity. Most insects have two pairs, but many 

 sluggish females and parasites like lice and fleas have lost 

 them. On the other hand, there is no reason to believe 



