31. However, some echinoderms have developed bilateral symmetry secondarily. 32. Reflectional symmetry, linear symmetry, mirror symmetry, mirror-image symmetry, or bilateral symmetry is symmetry with respect to reflection. 33. Secondary elements are positioned either side of main structures as two wings to maintain overall bilateral symmetry . 34. The subset of Young's lattice lying below these partitions has both bilateral symmetry and 5-fold rotational symmetry. 35. Bilateral symmetry is not easily broken.36. This results in a bilateral symmetry . 37. A very important feature in Chinese architecture is its emphasis on articulation and bilateral symmetry , which signifies balance. 38. This may represent a stage in the evolution of bilateral symmetry " from a presumably radially symmetrical ancestor ." 39. The surface is folded, and comes out with bilateral symmetry do to the shape of the case or shell. 40. It is usually around 0.7 centimeters long ( approximately the size of a fingernail ) and has bilateral symmetry .
