| Such a scenario would also explain why the lancelet amphioxus, a 'primitive' chordate, has a notochord with both cartilage and muscle. |
| There is a huge gap between the lancelet and the true vertebrates. |
| The human heart may present in degenerates all types from the pulsating vessel found in the lancelet up to that of the mammal. |
| The development of the lancelet presents us with an instance of the two-layered larva, or Gastrula. |
| The lancelet also differs from the true vertebrates, in that it has no limbs. |
| It is still more remarkable than the amphioxus or lancelet, which has been long known. |
