Note on rhinoceros thyroid gland constitution

In the absence of direct embryological information an estimation of rhinoceros thyroid gland constitution is essayed on the basis of indirect evidence provided by a study of 22 rhinoceros thyroid lobes, representing all available rhinoceros species. It is concluded that the rhinoceros thyroid gland comprises two embryonal elements, deriving from the thyro-glossal duct and from the 4th pharyngeal pouch, responsible respectively for its ventral and dorsal portions.