72 Laboratory Guide in Zoology 



of the scales. What difference is to be seen at the edge 

 of the wing ? 



X. — Scrape off a few of the scales on a glass slide and 



study with the high power of the microscope. Notice 

 the structure and the difference in shape. Draw iive 

 specimens, each different from the others. 



XI. — Scrape off a few of the hair-like scales from the 

 thorax and study them in the same way. Can you find 

 any scales intermediate between the short, broad ones 

 and the long, hair-like ones ? 



XII. — Count the abdominal segments. If necessary, 

 remove some of the hairy covering to show the joints. 



XIII. — Rub off the scales from the sides of the body 

 and find the spiracles. How many are there .' 



XIV. — Is each segment made of four parts — tergite, two 

 pleurites, and sternite — as in other insects .■• 



XV. — Make a drawing of the butterfly as seen from above 

 when its wings are expanded. 



THE SPIDER 



I. — Segmentation of the Spider. Notice how the body axis 

 is divided into two great divisions by a deep constric- 

 tion near its middle. The anterior division is made 

 up of the head and thorax, and is called the cephalo- 

 thorax. The posterior division is the abdomen. How 

 does this division of the body axis compare with that 

 of the lobster ? Notice the entire absence of any 

 segmentation either in the thorax or abdomen. 



II. — Appendages of the Head. The parts of the head 

 must be studied with the low magnifying power. Are 

 there any antennae ? Scattered over the anterior part 

 of the head find the small black ocelli, — generally four 



