266 ZOOLOGY. 



Comparisons. 'Compare the sow-bug with the cray-fish as to the 

 degree of union of head and thorax; the number of segments represented 

 in each of the three regions; the degree of differentiation among the 

 appendages; the mode of respiration; the presence of both exopodite and 

 endopodite; as to food, and habits. 



Physiology and Ecology. A study and report of the animal's habitat, 

 food habits, methods of motion, sensitiveness to light and to other classes 

 of stimuli, should be made. How does Oniscus behave when touched? 

 Do you find any trace of eggs or young? What facts are to be noted con- 

 cerning them? 



300. Cyclops. These minute freshwater Crustacea may be found in 

 almost any pool where aquatic plants are found. They flourish well in 

 aquaria. Select several of the larger specimens with egg masses one on 

 each side the abdomen. Examine in a watch glass with a little water to 

 which a drop of chloroform has been added. Use low power of microscope. 



General Form. (Study both dorsal and ventral surface.) 

 Cephalo-thorax : 



Anterior portion covered with the carapace. How many segments 

 represented ? How can we know that this is not merely the head, 

 or the whole cephalo-thorax ? 

 Posterior portion (four free thoracic segments). How is it known 



that these are not abdominal segments? 

 Abdomen : form ; number and character of the segments. 

 Appendages. Antennae, oral, thoracic, abdominal. Number and general 

 character of each. Where and how are the egg-cases attached? 

 Sense Organs. 



Eye spot (appearing as one, from which the name Cyclops). 

 Do you find any organs which suggest a tactile function? 

 Report on all available points of physiology: as food habits; methods 

 of locomotion; reaction to light and other stimuli. 



301. Comparisons. Collect all the minute fresh-water Crustacea pos- 

 sible and compare them with Cyclops. Learn to identify them by their 

 manner of moving in the vessels of water. Daphnia is especially favorable 

 for microscopic study on account of its semi-transparency. 



302. Spider (any common species large enough for study). 

 General Form. Study the relations of head, thorax, and 



abdomen. Are there any antennae? Oral appendages? Num- 

 ber and character of the thoracic appendages? Does the ab- 

 domen show any signs of segmentation? Has it any append- 

 ages ? Make sketches showing a ventral and a lateral view. 

 Special Organs. 



Examine the head with a hand lens and locate the eyes. 



Note more particularly the types of appendage found, 



