V. Memmler 1943 Perognathus californicus June 15, M.V.Z. After weighing and measuring the infants today Dr. Benson + I made a microscopic examination of the pelage. We found that there are 3 hair to a follicle at present in the infants. The central hair is dark with a light tip. It is this tip that extends so very long in the rump region, giving a halo-like appearance. The other two hair have a black tip and a yellow band beneath. These hair have now come out to the base of the sub-marginal band. There was no sign of new hair, coming in at shorter length than that of the rest. A live juvenile was examined and found to have mostly 3 hair to a follicle also. There were some 5 to a follicle. An adult examined had mostly 5 hair to a follicle and some 7. From this it is believed that the infant pelage nearly elongates to become the juvenile. Since the darker part of the hair is that which has already come out on the infants, it explains the present darker (brownier) appearance of the infants as compared to that of the juvenile which is quite grey. The hair is sparser in the region