Three white cats that had blue eyes and no tapetum were studied by behavioral, electrophysiological, and anatomical methods in order to determine whether they showed evidence of abnormal retinofugal pathways comparable to those found in Siamese cats and in other mammalian forms having melanin deficits. The three cats were normal in every respect. However, several other white cats, obtained subsequently, do show an abnormality of the retinogeniculate pathway identical to the abnormality of Siamese cats. Cats of the second type are thought to be homozygous for the Siamese gene and also the express the White gene. Because the characteristics Siamese pigmented "points" fail to develop in the presence of the white gene, cats of the second type are not distinguishable from other white cats on the basis of eye color or coat color. In terms of their central visual pathways and of their patterns, however, they are recognizably Siamese. It is not known how common "crypto-Siamese" cats are in the white cat population, but the possibility of their occurrence suggests that, in general, white cats should not be used for studied of the central visual pathways.