AMPHIOXUS, or Lancelet, the name of small, fish-like, marine creatures, forming the class Cephalochorda, of the phylum Vertebrata.
Ope yxta, gills), the fourth of the five classes of animals constituting the phylum Mollusca.
GASTROPODA, the second of the five classes of animals constituting the phylum Mollusca.
Ii.) except that Phylum 17, Diplochorda (a name doubtfully applicable to Phoronis) is replaced by Podaxonia, a term employed by Lankester in the 9th edition of this encyclopaedia and now used to include a number of groups of doubtful but possible affinity.
Vertebrate palaeontologists were slow to grasp this principle; while the early speculative phylogenies of the horse of Huxley and Marsh, for example, were mostly displayed monophyletically, or in single lines of descent, it is now recognized that the horses which were placed by Marsh in a single series are really to be ranged in a great number of contemporaneous but separate series, each but partially known, and that the direct phylum which leads to the modern horse has become a matter of far more difficult search.
TREMATODES, or flukes (as they are called from their fish-like shape), one of the three classes that compose the phylum Platyelmia.
P. Lamarck's term Annelides, now used to denote a major phylum or division of coelomate invertebrate animals.
It is not improbable that the three genera of this ancient phylum survive as types of a blindly-ending branch of the Gymnosperms; but be that as it may, it is in the Gnetales more than in any other Gymnosperms that we find features which help us to obtain a dim prospect of the lines along which the Angiosperms may have been evolved.
CHITON, the name 1 given to fairly common littoral animals of rather small size which belong to the phylum Mollusca, and, in the possession of a radula in the buccal cavity, resemble more especially the Gastropoda.
The Phylum Appendiculata similarly branches into sub-phyla, viz.