trouble telling the sex of my herman tortoises

by tom samotyj
(somerset)

hi there,

im having trouble like most people do telling the sex of my 2 herman tortoises. im interested in knowing because im worried they may fight if both are male when they come to a more mature age, also because i like to know if my pets are a he or a she. ive surfed the net to find answers but everybody seems a little vague. ive enclosed sum pictures of their undersides to see if you can help me resolve my problem. the smaller tortoise (roxy) is 2 years old and approx 2.5 inches in diameter. the larger tortoise (verne) is 3.5 years old and has a shell of approx 5 inches in diameter. hope you can help me

many thanks
tom samotyj