Please, Where´s the error? c#

It sais ¨Unexpected symbol `;' in class, struct, or interface member declaration¨ where is the error?

 using System.Collections.Generic;
 
 public class ModifiedStat : BaseStat {
     private List_mods; //A list of Attributes that modify this stat
     private int _modValue; //The amount added to the baseValue from the modifiers
     
     public ModifiedStat() {
         _mods = new List();
         _modValue = 0;
     }
     
     public void Addmodifier( ModifyingAttribute mod) {
         _mods.Add(mod);
     }
     
     private void CalculateModValue() {
         _mods = 0;
         
         if(_mods.Count > 0)
             foreach(ModifyingAttribute att in -_mods)
                 _modValue += (int)(att.attribute.AdjustedBaseValue * att.ratio);
     }
     
     public new int AdjustedBaseValue {
         get{ return BaseValue + BuffValue + _modValue; }
     }
     
     public void Update() {
         CalculateModValue ();
     }
 }
 
 public struct ModifyingAttribute {
     public Attribute attribute;
     public float ratio;
 }