172 CHORDATA. 



The complete degeneration of the tail and the final rotation 

 into the position of the adult can be traced in a series of indi- 

 viduals. 



Drawings of an adult individual, of a larva, and of a young 

 individual are desirable. 



SALPA CORDIFORMIS. 



Examine a specimen in a bowl of water without dissecting. 

 Use a hand-lens. 



Sexual form (occurring in chains) : 



1. Note the transverse muscle hands. How many bands are 

 there? Are they complete or interrupted? Do you know what 

 they are for? 



2. The oral aperture is dorsal and far forward. Are there 

 any muscles for opening and closing it ? 



3. What is the form and position of the cloacal aperture? 

 Is it provided with muscles? 



4. Observe the processes of the tunic, one anterior, one mid- 

 ventral, and two posterior. These processes (except the dorsal 

 posterior) serve to unite the individuals of the chain. 



5. Does the animal show perfect bilateral symmetry? 



6. Posterior to the mouth, the ganglion and the pigmented 

 eye-spot may be found. Immediately anterior to these is the 

 elongate hypophysis. 



7. Note the endostyle in the floor of the pharynx, and the 

 dorsal lamina between the pharynx and atrial cavity. From the 

 anterior end of the dorsal lamina the peri-pharyngeal hands 

 extend to the anterior end of the endostyle. 



8. The pharynx communicates laterally with the atrium b}^ 

 means of two very large stigmata. These are probabl}^ homol- 

 ogous with the numerous stigmata of ]\Iolgula. 



9. The ''nucleus,''^ the large mass in the posterior end of the 

 body, contains the stomach and intestine. 



The ova are fertilized by spermatozoa from individuals of 

 another chain, since in the same chain the spermatozoa 

 mature much later than the ova. The fertilized ova migrate to 



