Párrafo breve pero revelador: Todos, especies, géneros y familias; todos descienden de antepasados comunes. Pero, atención: Todos pero cada uno dentro de su propia clase o grupo. Fuera de su propia clase o grupo, no. 785.   Finally, the several classes of facts which have been considered in this chapter, seem to me to proclaim so plainly, that the innumerable species, genera and families, with which this world is peopled, are all descended, each within its own class or group,…