You did not provide any information about the map snippet you originally posted -- the date, location, or company, for example -- making this question extremely difficult to answer. Fortunately, you'll be happy to know that I was able to figure out all of those answers for myself.
The cartographer's use of labeling was quite prolific in the book containing your map. The symbol you inquired about appeared frequently on pages other than the one for the area you were interested in. I'm assuming that you wanted to keep this location's name to yourself, so I removed any potentially identifying features from the following graphic, which contains several instances of your symbol as it appeared on another page.