ONISCUS, CAPRELLA, BRANCHIPUS 185 



number and shape in male and female? The first represents 

 the head with two fused thoracic segments. The abdomen 

 forms a minute protuberance at the posterior end of the body. 



2. At the anterior end of the body are the eyes, two pairs 

 of antennae, a pair of maxillipeds, and a pair of legs. 



3. At the hinder part of the body are three pairs of legs. 



4. Near the middle of the body of the female, and near 

 the anterior end in the male, is another pair of legs. 



5. On two of the segments which do not bear legs are 



gills. 



If time 'permits, make a drawing. 



BRANCHIPUS (Fairy Shrimp) 



These animals may be found in pools of fresh water in 

 the early spring, just as the ice is leaving. Their method of 

 swimming by means of the large, expanded appendages should 

 be observed. 



1. Into what parts does the body seem to be divided? 

 Do all of these parts show segmentation? 



2. Find the following organs. 



(a) The stalked, prominent eyes. 



(b) The antennae. In the female the first are slender 

 and the second vestigial. In the male the first are slender 

 and the second are enormously enlarged to form a clasping 

 organ. 



(c) The labrmn forms an upper lip. 



{d) The mandibles, beneath the labrum and by the sides 

 of the mouth. Do they have cutting edges? 



(e) Vestigial maxillae behind. the mouth. 



(/) Swimming appendages. How many are there? Notice 

 the fringe of hairs on each. What are these for? Remove 

 one and examine it with a microscope. The lobes have been 

 described as exopod and endopod, but their exact relation- 

 ship is not certain. 



A drawing is desirable. 



