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Published online by Cambridge University Press: 20 November 2018
Zarhin proves that if  
 $C$  is the curve  
 ${{y}^{2}}\,=\,f(x)$  where  
 $\text{Ga}{{\text{l}}_{\mathbb{Q}}}(f(x))\,=\,{{S}_{n}}$  or  
 ${{A}_{n}}$ , then  
 $\text{En}{{\text{d}}_{\overline{\mathbb{Q}}}}(J)\,=\,\mathbb{Z}$ . In seeking to examine his result in the genus  
 $g\,=\,2$  case supposing other Galois groups, we calculate  
 $\text{En}{{\text{d}}_{\overline{\mathbb{Q}}}}(J)\,{{\otimes }_{\mathbb{Z}}}\,{{\mathbb{F}}_{2}}$  for a genus 2 curve where  
 $f(x)$  is irreducible. In particular, we show that unless the Galois group is  
 ${{S}_{5}}$  or  
 ${{A}_{5}}$ , the Galois group does not determine  
 $\text{En}{{\text{d}}_{\overline{\mathbb{Q}}}}(J)$ .