Another pelvic character of some interest is the blending of the pubis and ischium of the right and left sides in the middle line of the body. There are some genera of Dinosaurs like the English Aristosuchus from the Weald, and the American genera Coelurus, Ceratosaurus, and others, in which the pubic bones, instead of uniting at their extremities, are pinched together from side to side, and unite down the lower part of their length, terminating in an expanded end like a shoe, which is seen to be a separate ossification, and probably formed by a pair of ossifications joined in the median line. This small bone, which is below the pubes, and in these animals becomes blended with them, we may regard as a pair of prepubic bones like those of Pterodactyles and Crocodiles, except that they have lost the stalk-like portions, which in those animals are developed to compensate for the diminished length of the pubic bones. The prepubic bones may also be developed in Iguanodon, in which a pair of bones of similar form remains throughout life in advance of the pubes, as in Pterodactyles. In those Dinosauria with the Bird-like type of pelvis the pubic bone is exceptionally developed, sending one process backward and another process forward, so that there is a great gap between these diverging limbs to the bone. In the region behind the sternum to which the ribs were attached, and in front of the pelvis, is a pair of bones in Iguanodon shaped like the prepubic bones of Dimorphodon. They have sometimes been interpreted as a hinder part of the sternum, but may more probably be regarded as a pair of prepubic bones articulating each with the anterior process of the pubis (see Fig. 80). The small bones found at the extremities of the pubes in such carnivorous Dinosaurs as Aristosuchus are blended by bony union with the pubes. The bones in Iguanodon are placed behind the sternal region without any attachment for sternal ribs, and the expanded processes converge forwards from the stalk and unite exactly like the prepubic bones of Ornithosaurs. While this character, on the one hand, may link Pterodactyles with the Dinosaurs, on the other hand it may be a link between both those groups and the Crocodiles, in which the front pair of bones of the pelvis has also appeared to be representative of the prepubic bones of Flying Reptiles (see Fig. 32, p. 98). [Illustration: FIG. 80. DIAGRAM OF THE PELVIS SEEN FROM BELOW IN AN ORNITHOSAUR AND A DINOSAUR]