Quast 1948 Journal 142 June 26 Mayo Mina Dol de Mier Calmalli, Baja California entrance with enough space left at its top for one man to squeeze through at a time. We entered the tunnel and followed the iron cart rails until a vertical shaft was reached about 150 feet back in the mine. The shaft dropped for five or six levels, perhaps more, it not being mines - targeted at the lowest ones. One or two large bats were seen when we reached the end of the cart line but they were not obtained. They others went down the shaft and while waiting for them I noticed a small crack in the roof above the shaft that had been closed by wooden planking. Several bats flew into this area but were not identified due to the fact that my flashlight was not working. Attempts at netting them as they flew by in the dark were futile, but they seemed to be very nervous and restless due to our entrance and the noise of the others of the group investigating the lower levels of the mine. Only one bat was obtained here and that by Tevis down in the lower levels of the shaft. It turned out to be Macrotus californicus. We then investigated the tunnel north of and below the first one. As we passed through the iron gate at its entrance, we disturbed hundreds of large flies, but were