96 ANNELIDA 



On the peristomium find the two tentacles and a tentacular 

 cirrus on each side. 



3. On the succeeding somites study the parapodia. Ob- 

 serve the large dorsi cirri and the knoblike notopodium 

 with the short unjointed setae. There is no neuropodium. 



4. Identify the pharynx, gizzard, and intestine. 



5. Compare the sexual bud with the nonsexual individual. 

 The adult male and female differ. The outer prostomial 

 tentacles of the male are forked. Is this bud to be a male 

 or a female? In an older sexual individual make out a so- 

 called thoracic region in which the setae are short, and an 

 abdominal region in which the setae are long. Look for evi- 

 dences of germ cells in the body cavity, between the intestine 

 and body wall. There is a ventral brood pouch on the adult 

 female and the young partly develop in it. Find the anal 

 cirri. 



A drawing illustrating the method of reproduction should 



be made. 



LEPIDONOTUS (POLYNOE) SQUAMATUS 



The family Aphroditidae, to which this belongs, can be 

 distinguished from all others by the presence of peculiar 

 plates (elytra) on the dorsal surface. They lead sluggish 

 lives under stones and are carnivorous. Note the size, color, 

 and shape of the worm. 



1. Examine the elytra. How are they arranged? What 

 purpose do they serve? How many are there? With a hand 

 lens observe the fringed condition of the outer edge and the 

 small tubercles covering the surface. Note the color of the 

 elytra and the notches in the inner edges of the posterior pair. 



Remove with forceps all of the elytra on one side of the 

 specimen and the first two or three on the other side. Note 

 the stumps to which the elytra were joined. Do all seg- 

 ments have elytra? If not, do the scaleless segments have 

 structures which correspond to elytra? 



2. Examine the dorsal aspect of the head, and note the 

 small prostomium, with two pairs of eyes, three slender ten- 



