was increased to eighteen; all other crocodiles have but fifteen or sixteen. The trunk was long, another adaptation to water life. There were two firmly united vertebrae in the sacrum, as in the modern forms. The reason for the persistence of this terrestrial character we shall see later. [Illustration: FIG. 109.—Tail, scapula (_sc_), and coracoid (_c_) of _Geosaurus_. (After Fraas.)] The tail was very long and strong, nearly as long as all the remainder of the body, and relatively much longer than in other crocodiles. It is of interest to observe that the head, neck, body, and tail had almost the same relative proportions as those of the great sea-lizards, the mosasaurs. The terminal bones of the tail are very peculiar, and very different from the corresponding bones of other crocodiles. While the spines of the tail bones along the anterior part are only moderately stout and long, and are directed obliquely backward, near the terminal part they become suddenly much broader and are directed upward, and, a little farther along, obliquely forward. The chevron bones on the under side also here become broader and longer. The end of the tail curves markedly downward to end in a slender point. It will be remembered that a similar downward curvature of the end of the tail observed in nearly all specimens of ichthyosaurs induced in Owen the belief that the animals had a fleshy terminal fin, a belief which later discoveries of the carbonized remains of the flesh confirmed. The peculiar structures observed in various specimens of these sea-crocodiles, even though no impressions or remains of the fleshy parts have been discovered, is quite conclusive evidence that these animals also had a broad, fleshy, terminal fin. No other explanation of the structure is possible. [Illustration: FIG. 110.—_Geosaurus._ Elongate hind leg, and paddle-like front leg. (After Fraas.)] The ribs are not at all stout and are not much curved. They are directed posteriorly in the known specimens preserved in the matrix in such a way as to indicate a slender thorax and abdomen, not the broad body of the modern crocodiles. The abdominal ribs, that is, those protecting the region on the under side of the body between the breast bone and the pelvis, are strongly developed in _Geosaurus_. The sternum, always present in other crocodiles, is wanting in _Geosaurus_. The shoulder-blades and coracoids, often changed in shape in water reptiles, are not unlike those of the amphibious crocodiles, but are smaller and flatter.