quadrangle
n
1 plane figurewith four sides, esp a square or rectangle 四边形; (尤指)正方形, 长方形.
2 (fml 文) four-sided courtyard surrounded by large buildings, eg in an Oxford college (四周由大型建筑物围绕的)方形庭院(如於牛津大学学院的).
And why only snakes? Cats, for instance, would be greatly helped; no running fights with large, fierce rats or tussles with grown rabbits -- just a bite and no more effort needed.