今のとこコードは
molS = GameObject.FindGameObjectsWithTag("MoleugeS");

Dictionary<string, float> DictionaryX = new Dictionary<string, float>();
Dictionary<string, float> DictionaryY = new Dictionary<string, float>();
foreach (GameObject objS in molS)
{
DictionaryX.Add(objS.name, objS.transform.position.x);
DictionaryY.Add(objS.name, objS.transform.position.y);

}

List<float> posX = new List<float>(DictionaryX.Values);
List<float> posY = new List<float>(DictionaryY.Values);

posX.Sort();
posY.Sort();
if (isRight) currentPosLimit.x = posX[posX.Count -1 ];
else currentPosLimit.x = posX[0];

こんな感じで、右端又は左端と最下段を取ってます