The enclosure includes a stationary panel having a depression formed in one otits faces.An opening is formed in the depression. A door is inset in the depression andit too is providedwith an opening. The door reciprocates from an open position in which the twoopenings are sideby side one another to a closed position in which the openings are no longerside by side. Whenthe door is open, a passage is opened from outside the enclosure to itsinterior through which ananimal may enter and depart from the enclosure. When the door is closed, soalso is the passage.
