NEF filed being forced into JPEG upon import

I'm using a Nikon D3100 and have just started using Lightroom. My camera took RAW and JPEG photos and when I choose the NEF (Nikon's version of RAW files) photos to import, Lightroom forces them into JPEG format. How can I stop this from happening? 

I'm running a Mac with the newest OS installed and I've downloaded the Camera Raw plug-in (though I'm not 100$ sure how to access that).