Mutual Inductance - Self Induced Voltage
The diagram is correct. The dot markings indicate the polarity of the primary and secondary windings such that when instantaneous current enters the primary it comes out of the secondary as if the primary side circuit were directly connected to the secondary circuit.

Your primary has a voltage source vg, the secondary winding in this diagram will have vg present across it with the plus side at the top of the winding and the negative of vg being at the dotted end of the secondary transformer.