522 The Animal Kingdom 



siderable economic importance as crop destroyers. The one which is 

 to be studied in detail here is the large lubber grasshopper of the south- 

 eastern United States, Romalea sp. 



The External Anatomy of Romalea sp. — The external an- 

 atomy of the grasshopper shows many features highly reminiscent of 

 the crayfish. The body is covered with the heavy exoskeleton of chitin 

 that must be molted at intervals as the animal grows. The exoskeleton 

 is actually composed of chitinized plates, the sclerites, which are sepa- 

 rated by softer materials. The head bears a number of sensory struc- 

 tures, including the jointed antennae with sensory hairs. The antennae 

 are chiefly tactile but may also be important as chemical receptors. There 

 are two lateral compound eyes constructed on the same pattern as the 

 compound eye of the crayfish. Three simple eyes, or ocelli, are also 

 present : one in the median portion of the head between the antennae, 

 and one just medial to each large compound eye. While the head 

 sclerites are united, certain regions are evident. The dorsal region 

 is known as the vertex, the lateral the genae or cheeks, and the anterior, 

 the jrons. Ventral to the frons is a broad plate, the clypeus, and ven- 

 tral to the clypeus are the mouth parts. These are of the chewing type 

 and are quite generalized in structure. They consist of the upper lip 

 or labrum fastened to the clypeus, two lateral jaws, the mandibles, a 

 pair of maxillae, a lower lip or labium, and a median hypopharynx or 

 tongue. Each maxilla consists of several parts, a basal portion, the 

 lacinin, galea, and palp. The labium consists of a basal submentum 

 bearing the mentum and the ligula which forms the lip, and a pair of 

 sensory palps. 



There are three regions in the thorax : the prothorax, the meso- 

 thorax, and the metathorax. Each of these regions is formed of four 

 portions: a dorsal tergum, two lateral pleura and a ventral sternum. 

 Both the tergum and pleura are formed of several plates fused together. 

 The dorsal part of the prothorax is large and saddlelike, extending 

 dorsally over the mesothorax and is known as the pronotum. Each 

 region of the thorax has a pair of legs, with each consisting of several 

 segments: a short proximal coxa, an even shorter trochanter, a jemur, 

 tibia, and tarsus. The tibia has rows of spines, and the tarsus has three 

 small segments, with the proximal bearing four pairs of ventral pads 

 and the distal one with two claws and a pulvillus, a fleshy structure. 

 The third pair of legs is highly modified for jumping and has a broad 

 flat femur containing many muscles. Two pairs of wings are present 



