DINGS A.URIA. 



than the tibia. The astragalus aud calcaneum are small, neither with any 

 process; and only two bones have been observed in the distal row of the 

 tarsus. There are four functional digits in the hind foot, and the fifth is 

 represented by its metatarsal. The phalangeal formula is 2, 3, 4, 5, 0. 

 The first digit, however, is so much shorter than the second, third, and 

 fourth, that this foot would probably make a three-toed track like the 

 supposed bird-tracks of the Connecticut Triassic sandstone, in which 

 the only known remains of Anckisaurus have been found. 



Other Triassic Theropoda, known by more fragmentary 

 specimens, are described under the names of Zanclodon or 

 Teratosaurus (Wlirtemberg), Dimodosaurus (France), Theco- 

 dontosaurus (Bristol, England), Ornithosuchus (Elgin, Scotland), 

 Euskelesaurus (South Africa), and Massospondylus (South 

 Africa and India). Numerous fragments of later date, both 

 Jurassic and Cretaceous, found in Europe, are named Megalo- 

 saurus. One nearly complete small skeleton from the Litho- 

 graphic Stone (Lower Kimmeridgian) of Bavaria, known as 

 Compsognathus longipes, seems to exhibit an embryo within the 

 abdomen. The best known skeleton of a Jurassic genus is that 

 of Ceratosaurus from North America. 



Ceratosaurus (fig. 120). The skull in this genus is relatively large 

 and very delicate in construction. The nasal bones are firmly fused 

 together and support a large median horn-core ; the premaxillaries are 

 separate and toothed ; the prefrontal bone partly overhangs the orbit on 

 each side. The usual vacuity occurs in the hinder half of the mandible. 

 All the cervical vertebrae, except the atlas, are strongly opisthocoelous, but 

 always flattened, not ball-shaped, on the anterior face of the centrum. 

 The other vertebral centra are slightly amphicoelous, and five are co-ossified 

 in the sacrum. Each sacral rib is supported by two vertebras. The tail 

 is long, compressed and deepened in its anterior portion, as indicated by 

 the considerable length of the chevron bones. The fore limbs are very 

 small, and the humerus is short, with a strong radial crest. The carpal 

 bones are only imperfectly ossified, and there are four digits (i to iv) in 

 the manus, each bearing a claw ; nos. n and in are much larger than 

 nos. I and iv. The elements of the pelvis differ from those of all other 

 known Dinosaurs, except the Cretaceous Ornithomimus, in being fused 

 together. The symphysis both of the pubes and the comparatively slender 

 ischia is much expanded, forming a kind of " foot." The femur is much 

 curved and somewhat longer than the tibia ; the astragalus is not fused 

 with the latter, but exhibits a large ascending process. The hind foot 

 comprises only three digits, probably II iv., and the metatarsals are 

 unique among Dinosaurs in being fused together and with the distal row 



