CHORDATA 251 



Dolichoglossus kowalevskyi Agassiz 



An elongate worm-like animal made np of three 

 parts, a proboscis, a short neck and a trunk. The 

 trunk is usually orange-yellow, while the proboscis 

 is more pink with the collar a darker tint. It reaches 

 a length of about 6 inches. 



It may easily be mistaken for an annelid worm, 

 but may be recognized by its proboscis and neck. It 

 is often common, burrowing into the sand flats be- 

 tween tides from Massachusetts to North Carolina. 



TUNICATA 



These are degenerate chordates in which the 

 adult is cylindrical or globular and is encased in a 

 cuticular or cellulose covering called the tunic. The 

 most conspicuous tunicates are the Ascidians. 

 Some, the "simple Ascidians", are usually solitary 

 and attached to some solid object. Others, the 

 "Compound Ascidians" are largely colonial forms 

 embedded in a gelatinous substance. 



The larval stages are free-swimming and pos- 

 sess a notochord. Later they assume a sedentary 

 habit and undergo considerable changes in structure. 

 In this process of degeneration, the notochord dis- 

 appears. 



Another group, the Thaliecea, comprise the 

 Salpas, pelagic tunicates which are abundant on the 

 surface of most seas. 



