The Dog Law Enforcement Officer shall, at least once a month, make a return to the Director of Public Safety, under oath or affirmation, of moneys received by or through him or his assistants, by virtue of his office, or on account of any matter connected with his office. Immediately upon making such return, he shall pay over such amount to the City Treasurer, which shall become a part of the General Fund. He shall in like manner pay into the City treasury all fees received by him from the Commonwealth on account of the humane disposition of dogs, as well as any moneys received from the public or private sale of dogs. (1944 Code Ch. 3 §21.)