"Four parathyroid glands are present on the back side of the thyroid gland, one pair each in two lobes of the thyroid gland" [ pg 334]... Hw is this possible???

It is possible....he means that these 4 parathyroid glands are arranged in 2 pairs. Now each pair has 2 lobes. Here, each lobe is counted as 1 parathyroid gland , thus, resulting in 4 parathyroid glands.

Hope you got it!!!