80 ANNELIDA. 



AUTOLYTUS CORNUTUS. 



This polychaete lives in cylindrical tubes of its own con- 

 struction that it attaches to seaweeds and hydroids, and is espe- 

 cially interesting because of its method of reproduction, by bud- 

 ding. 



Study live and preserved specimens with the naked eye and 

 with the hand-lens, in order to form a correct idea of its natural 

 color, size, and movements, and then study stained specimens 

 with the low power. 



1. Observe two individuals attached end to end. The ante- 

 rior one is a non-sexual zooid (or original "stock") and is giving 

 rise to a new sexual zooid by 'budding. Counting the peristomium 

 as one somite, on what somite does the bud begin and what 

 does it represent? 



2. Study the head of the anterior, non-sexual zooid. Find three 

 prostomial tentacles. How are they arranged? Find the eyes. 

 How many pairs are there? Do you find palps? On the peri- 

 stomium find the two tentacles and a tentacular cirrus. 



3. On the succeeding somites study the parapodia. Observe 

 the large dorsal cirri and the knob-like notopodium with the short 

 un jointed setae. There is no neuropodium. 



4. Identify the pharynx, gizzard, and intestine. 



5. Compare the sexual bud with the non-sexual individual. 

 The adult male and female differ. The outer prostomial tenta- 

 cles 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 evidences 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. 



