On my theory, unity of type is explained by unity of descent.

根据我的理论， 类型的统一可以用血统的统一来解释。

By unity of type is meant that fundamental agreement in structure which we see in organic beings of the same class, and which is quite independent of their habits of life.

类型的统一意味着我们在同一纲的有机生物中看到的结构上的基本一致， 并且完全独立于它们的生活习惯。