152 ABTHROPODA. 



2. The eyes are not stalked. Are they compound? 



3. The second antenna of the male are very large. Compare 

 them with the first antennae and with the antennse of a female. 



4. Around the mouth are the labrum, forming an upper lip, 

 the first maxillipeds (fused), forming a lower lip, and between 

 them the mandibles, first maxilla, and second maxillae. 



5. Examine the appendages behind the mouth. How many 

 are there? How many bear claws? Compare these claws with 

 those of a lobster, and see how they differ. Which appendages 

 are used in crawling? Why are some of the appendages arranged 

 so they can be twisted around by the sides of the animal ? What 

 are the remaining appendages used for? 



6. Spread the appendages apart and find the gills, which are 

 attached to the bases of the appendages. 



Make a drawing of the animal. 



Smallwood: The Beach Flea: Talorchestia longicornis. Cold Spring Har- 

 bor Monogr., 1, 1903. 



PORCELLIO OR ONISCUS. (Sow-Bug.) 



These animals occur in damp places, such as under stones, 

 logs, etc., and in cellars. They live for the most part on decaying 

 vegetable matter. To what class of the Arthropoda do they be- 

 long? 



1. Notice the shape. Is this an adaptation? 



2. Is the body divisible into head, thorax, and abdomen? 

 Count the number of segments. Is there any evidence of fusion 

 at the posterior end of the body? 



3. Examine the appendages. 



(a) Are the eyes stalked or sessile? 



(6) Only one pair of antennae is present, the first pair being 

 rudimentary. 



(c) The mouth appendages are small. They consist of man- 

 dibles, two pairs of maxillce, and one pair of maxillipeds. 



(d) How many walking legs are there? Are these all alike? 



(e) Notice the character and number of the abdominal appen- 

 dages. On the posterior surface of all but the last pair, which 



