I'll VIA' M Ain Uli'ol'nDA 105 



of the aiKil opcninji. On cacli side, projecting from hcncatli llir 

 caudal l)()rdor of tlio tenth torguin, is a pointed appendant' 

 termed the nrnis (phjral, cerri). These are generally re^sarded 

 as the modified appenda^jes of the tenth segment. I'^ach cercus 

 partially covers a much larger, triangular sclerite which ext^'nds 

 from the lateral border of the tenth tergum caudad. These are 

 the podical plates. 



In the male the hroad ninth sternum is followed hy a houd- 

 shaped tenth which forms the caudal end of the body and 

 terminates dorsad in two points. This is commonly called the 

 subgenital plate as it forms a hood about the genital apparatus. 



The most prominent portion of the caudal part of the abdomen 

 of the female is the ovipositor, composed of two pairs of rigid and 

 pointed pieces and employed in forming a hole in the ground 

 within which the eggs are deposited. Between the ventral pair 

 is the opening of the oviduct. From the median caudal margin 

 of the eighth sternum a pointed projection, the egg guide, extends 

 caudally l)etween the ventral pieces of the ovipositor and aids in 

 placing the eggs. 



On the plate of the left lateral aspect of the female indicate 

 by means of brackets and labels the three divisions of the body. 

 These should be placed above the drawing. Label the various 

 external structures described for each region. The abdominal 

 segments may be numbered serially. The abdominal terga 

 and sterna may be designated by symbols, as, for example, /j 

 referring to the tergum of abdominal segment 2, and .^o referring 

 to the sternum of abdominal segment 2. 



Secure an animal of the other sex, study and label the struc- 

 tural modifications of the caudal end. 



It will he profitable to devote .some time to a comparison of the 

 figures of the crayfish and grasshopper with regard to body 

 regions and appendages including types, distribution, modifica- 

 tions, and functions. Such a study might be summarized in the 

 form of a table. 



