December 1956 Journal Apr 8 (cont) Point Isabel, Contra Costa Co., Calif. Many perlers [size] of Microtus (?) in runways. The ground here, a little ooma, is quite hard but the depression seemed to have been dug out (not formed naturally by earth cracking, etc) since it was so round. Maybe old nest of microtus? Grass in nest may have been the shreds of Sonicoenia stripped off by the animal but small torn up pieces of paper were scattered thru the nest too. Ground that the nest was in was about 3-4 ft above [illegible] water's edge but at least 150 ft horizontally from it. From the drift wood scattered around it would seem that at a very high tide the water would be only a few inches vertically below nest but normal tides would not come close to it. One small hillcock near by about 3-4 ft above [illegible] waterline gave 3 microtus (2 adult & 1 young). Sonicoenia about 6 inches high grew on it and was matted in most places to form a roof 2-3 in above ground. Many other runways with microtus or some manner droppings were seen under this mat. Runways were also present at edge of hillcock.