22 DARWINISM VERIFIED. [i. 



occur always at the bottom, among their least highly 

 developed species. Apes, bats, and rabbits are suffi- 

 ciently distinct in type, but the lowest members of 

 the orders to which these animals respectively belong 

 are strikingly like one another. At the bottom of 

 the mammalian class, the echidna and duck-bill have 

 many points in common with birds and reptiles ; 

 while birds and reptiles not only draw together so 

 that it is hard to distinguish their most primitive 

 forms as clearly bird or clearly reptile, but these 

 primitive forms remind one in many ways of the 

 batrachians. A batrachian, in turn, is an animal 

 which ends its life as a kind of reptile after having 

 begun it as a kind of imperfectly specialised fish. 

 Again, the lowest known vertebrate, the amphioxus, 

 usually ranked with fishes, though hardly specialised 

 enough to be called a true fish, exhibits marks of 

 actual relationship with the ascidian, which is nothing 

 more than a worm of the order known as tunicata. 

 No two animals could be less like each other than a 

 bee and a nautilus, yet in their lowest members the 

 two sub-kingdoms of articulata and molluscs become 

 barely distinguishable from each other and from the 

 worms with which the vertebrate sub-kingdom also 

 becomes blended. It is on account of this conver- 

 gence of types as we descend in the scale that 



