30. Presumption as to guilt in certain cases.- If any person is charged with the offence of killing a goat, cow or its progeny contrary to the provisions of clause (l) of sub-section (1) of section 11, and it is proved that such person had in his possession, at the time the offence is alleged to have been committed, the skin of any such animal as is referred to in this section with any part of the skin of the head attached thereto, it shall be presumed until the contrary is proved that such animal was killed in a cruel manner. | 