I'll YUM .\irriiii'(>i'(>n.\ \{):\ 



epicraniinn, in which thc^ dorsinn is spoken of as the rrih.r, the 

 sides as the gena, and the front as the Jranx. The frons extencis 

 ventrad to a distinct transverse suture, below which is a very 

 broad sclerite known as the clypeus. Attache(i to the ventral 

 l)order of the clypeus is a broad, freely moving flap, the upper 

 lip, or Idbruni. This is not a true appendage but a part of one 

 of the segments which enters into the composition of the head 

 skeleton. 



The head bears eyes, antenna?, and three pairs of mouth parts. 

 Note the two large, brown, oval areas on the dorso-lateral 

 portions of the head. These are the compound eyes. Remove a 

 portion of the cornea, clean out the pigment, and mount in water 

 on a slide. Are the facets of this cornea similar in shape to those 

 of the cornea taken from the eye of the crayfish? The gra.ss- 

 iiopper also has three simple eyes, or ocelli, one in the depression 

 of the middle of the frons, the other two cephalad of the dorsal 

 portion of the two compound eyes. The antennce are many- 

 jointed appendages springing from the space between the com- 

 pound eyes. Raise the upper lip and note a pair of heavy, black 

 mandibles. Determine the direction of their movements. Ju.st 

 caudad of the mandibles is the first pair of maxillce with feelers 

 or palps at the sides, and lying back under the head, bearing 

 palps on either side, is the second pair of maxillce which have 

 fused with one another to form the labium or lower lip. The 

 antenme and mouth parts of the grasshopper represent modifica- 

 tions of typical arthropod appendages. 



The Thorax and Its Appendages.— The thorax comprises three 

 segments, called the prothorax, mesothorax, and metathorax, when 

 named in order from the cephalic end. These divisions are 

 easily recognized by the appendages which they bear. One 

 pair of legs is attached to the ventro-lateral margin of each thor- 

 acic segment. In addition, the mesothorax and metathorax each 

 bears a pair of wings articulated with the dorso-lateral margin. 



Remove the wings from the left side and compare them. What 

 are your deductions? The wings arise as saclike evaginations of 

 the body wall. During development the two walls of the sac 

 become pressed together, forming a thin membrane. The veins 

 of the wings are respiratory tubes or trachea', filled with air, each 

 surrounded by a tubular blood sinus. After^the insect attains 

 its full size, blood ceases to flow in the wings and they become 

 the dry, hard, and lifeless structures of the adult. 



