sequence diagram question from UML beginner

[mike zhang]

suppose I have Class_A calls Class_B, then class_B calls class_C, and class_C calls class_A, and so on. In sequence diagram, I already have 3 obj for Class_A, Class_B, Class_C. To interpret that Class_C calls Class_A, should I draw an arrow back from Class_C object to the Class_A or should I draw another new Class_A object next to Class_C obj and add an arrow from Class_C obj to the new Class_A obj ?
Thanks,
Mike

[Mark Spritzler]

I believe you have an arrow going back to Class A.
Mark

[Pho Tek]

The mutual dependency between class A and C worries me. Are these entity objects ?
Pho

[Graeme Brown]

In sequence diagram you have instances of classes. So if instance of class C calls back to the original instance of class A then draw the line back. If C calls a new instance of A then add a second A.