# How do you properly define a line in a Feynman diagram?

I've been reading Tony Zee's "Quantum Field Theory" and I'm really enjoying it. However, on p. 45 I came across what I think is an inconsistency. The sentences in question are:

The rules go something like this:

(1) diagrams are made of lines and vertices at which four lines meet;

...

(3) for each line assign 1/m2;

Here's the thing: if a vertex is a point at which four lines meet, then most of his figures are wrong. Here are a few examples:

• Fig. 1.7.1b is listed as having four lines and one vertex, but if a vertex is a point where four lines meet then it has five lines.
• Fig. 1.7.1c is listed as having four lines and one vertex, but if a vertex is a point where four lines meet then it has six lines.

• Fig. 1.7.2b is listed as having six lines and two vertices, but if a vertex is a point where four lines meet then it has seven lines.

• Fig. 1.7.2c is listed as having six lines and two vertices, but if a vertex is a point where four lines meet then it has eight lines.

• Fig. 1.7.3b is listed as having seven lines and two vertices, but if a vertex is a point where four lines meet then it has eight lines.

The problems I noted disappear if you consider the loops I examined to count as one line when assigning the mass terms. However, this is not what Zee says. Is he wrong or am I missing something?