264 ZOOLOGY. 



Compare the appendages again by groups, and notice the chief points 

 of difference, and the ends served by these differences. Make a 

 careful sketch of each type of appendage, labeling all parts. (The 

 names of the segments of the larger appendages may be found in 

 fuller texts, if desired.) 



By studying the living specimen, determine just the work done by 

 each of the types of appendages. 



Note the position of the eyes. Examine with a low power. 



In the basal joint of each antenna is the opening of the " green gland." 



In the basal joint of the antennules are the otocysts. 



V. Gills. Examine the gill-chamber, and the position of 

 the gills therein. Which appendages bear gills? How many 

 tufts to each appendage? How do they differ as to the place 

 of their attachment? How many in all? Make a table showing 

 these facts. 



VI. Internal Organs. Remove with much care the carapace from the 

 thorax and the terga from the abdominal segments, by the use of scissors 

 and forceps. Sketch the organs in their natural position. What organs are 

 visible? 



Examine in some detail the following sets of organs, 

 (a) The circulatory organs. 

 Heart : just beneath the carapace, in a membranous chamber (peri- 



cardial sinus). 

 Apertures, by which the blood enters the heart from the sinus; 



dorsal, ventral, lateral. How many do you find? 

 Arteries ; anterior, posterior. 

 (The teacher should have, if possible, a permanent preparation of the 



lobster in which the arterial circulation has been injected with a 



colored mass.) 



VII. Reproductive Organs. These will be found immediately beneath 

 the pericardial sac as whitish (male), or yellowish to brown (female) 

 lobed structures. Depending on the sex there will be found 



Ovaries or testes. Form, position, and number of lobes? 

 Oviducts or vasa deferentia. Course, length and outlets? 

 Can you determine the sex of your specimen? Note especially the ex- 

 ternal differences between males and females. 



VIII. Digestive Organs. 



Liver, a pair of yellow, brown or reddish masses anterior to the re- 

 productive organs. 



Stomach ; sketch in position. Dissect later, if time allows, and note 

 the anterior and posterior chambers, and the grinding apparatus. 



How is the mouth situated relatively to the stomach? 



Follow the intestine backward from the stomach to the 

 Anus: position of? 



