Definitely a girl!
Like Paul said, "Female tails taper rapidly... ...Male tails taper less rapidly."
The taper described above is from the vent to the tail end. A female's reproductive organs are housed in the area just before the vent. A male's reproductive organs are housed after the vent, making the area immeditately before/after the vent the same thickness; a smoother, more gradual, taper.
Have a good one!
HH
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Due to political correctness run amuck,
this ol' hillbilly is now referred to as an:
Appalachian American