With no disturbance to blow its remains away, it rotted there and the stalagmite grew over it, so to speak. Scientists, estimating the rate of growth of stalagmites, were able to calculate approximately how long ago the bat had fallen. The head and wing bones were barely discernable. It is also known that the bats have moved around in the cave, for their tiny skeletons have been found in remote sections at points where the bats are no longer found clinging to the ceiling for their daytime sleep. Such findings indicate one of two possibilities; one, that some bats might have gotten lost in the cave and died there, away from their normal resting place, and, second, that previous openings have since been closed, due to various earth movements, forcing the bats to use new openings and thus change their location within the cave. Scientists place little credence on the former possibility because bats seldom get lost. They can find their way in any dark cave or passageway and know how to get out the same way they went in. The second possibility is the most likely, that centuries ago there were other openings to the cave through which the bats entered and spent the daylight hours. As old age overtook them they would die and fall to the floor. Then, as subsequent earth movements closed the openings, the bats would find new doorways to their daytime abode. This also accounts for large quantities of guano which were found in portions of the cave where no bats were to be seen sleeping on the ceiling above. There are eighteen species of bats to be found in New Mexico, and thirteen are known in the Carlsbad region. In the United States as a whole, scientists have classified over 251 varieties of these winged mammals. Of the thirteen found near the Caverns, eight are known to have made use of the cave at one time or another. Old skeletons have been found in remote sections of the cave which have been identified as those of the Large Pale Bat (_Antrozous pallidus_), wing bones of which were found in one of the innermost rooms; the Big Brown Bat (_Eptesicus fuscus_), a skull and wing bones having been discovered in an inner room; House Bat (_Myotis incautus_), several skull fragments of which were found in one of the lower rooms of the cave; Red Bat (_Nycteris borealis_), two old skulls of which were found on the floor of one of the deepest rooms; Cave Bat (_Myotis velifer_), evidenced by imperfect skull fragments found deep in the cave; Great Hoary Bat (_Nycteris cinerea_), largest of the northern bats, possessing silvery grey fur and not normally a cave dweller, but wing bones were found in the cave, indicating they may have lived there at one time, and the Little California Bat (_Myotis californicus pallidus_), whose presence was indicated by a skull picked up amid the dust and debris of a low, inner room.