Palæontology, like most other sciences, has attracted a large number of students since the first pioneers cleared the way for inquiry and brought the fossil remains into something like connected order. This increase in the number of inquirers has borne fruit in the immense variety of fossil remains that are scattered about in museums and private collections, the variety being now so great that it has become almost impossible for one person to study the whole of them, in consequence of which the majority of students confine themselves to the fossils of one formation or to the remains of a natural order, as Invertebrata or Vertebrata. Here, again, the application of a number of investigators to one distinct branch is bringing a further increase to our knowledge in that branch. Take the case of fossil fishes. It was quite possible twenty or thirty years ago for the great palæontologist Agassiz to describe and figure what, as the result of seventeen years of close study, was then known of the fossil fishes of all formations; but the stimulus that resulted from the publication of his work has piled up the list in a wonderful manner, so that it would be well-nigh impossible for any ordinary palæontologist to describe them all now in anything like a satisfactory way. This great amplification necessitates inquirers to confine themselves to the fish remains of a single formation, or to a particular part of the fish, as for example, the teeth.