History of Monsters. 569

# XVIII. A four-footed goldfinch with a woolly thistle.

Finally, among the causes for a fetus with redundant parts, we must include the scarcity of matter. Although this may seem absurd, it is by no means far from the truth. In cases where the available material is insufficient in quantity to produce two separate fetuses, yet too abundant for the formation of just one, the result is a single, monstrous birth. This occurs as the matter multiplies the legs and feet while generating the upper parts of the body as single and normal. Thus, we should keep in mind those causes which we previously mentioned in the general section on causes.