Help with graph apparently showing standard deviation with 2 values?!

#1
Hi,

I've got a presentation on a scientific paper this afternoon and am very confused with a graph in the paper (graph/dot plot C). I hope this doesn't break forum rules, I do believe this is a statistics question. Basically, in the plot on the far right (C), it shows values +/- standard deviation. However, the SD bars dont cover both values for each dose (x axis). From my understanding, SD with 2 points must be equal by definition as they are both equidistant from their mean.

Is this true, or am i understanding this plot very wrongly?

Many thanks

View attachment 6411
 
#2
It looks as if the long bar is the mean and the short bars show the SD. If this is the case, then there are a couple of down bars which have been missed by mistake.