Thacker 1958 Species Account. Microtus californicus Sept. 22 1.0 mi. N, 2.0 mi. E Martiney, Contra Costa Co., Calif. Again two Microtus. Although there are cuttings of grass I have not seen any of Salicornia. Sept. 23 Two more Microtus. I pull my traps. Dec. 21 San Pablo Creek (saltmarsh), Richmond, Contra Costa Co., Calif. Before setting traps I walked around the marsh. Salicornia is the principal vegetation in the lower areas, higher up grass takes over. The Salicornia here is much higher here and lacks the heavy matted layer that one finds at Martiney. Microtus sign was abundant. Everywhere I kept finding piles of cut Salicornia and fresh droppings. Under every board one would find great quantities of cuttings. Before dark I got out about 50 traps, a quick survey of the line as I returned from the farthest trap produced six mice. Dec. 22 This A.M. I had another 12 mice and one Lepus ornatus in this line. The line runs along a natural ditch in the marsh. I set out another 100 traps and had 6 mice as I returned along the line. George Fisher had 5 mice from the more grassy areas all of the ones he had seemed quite young. I discarded two ?? and one or 2 of under 30 grams.