marsh.] ALLOSAURUS. 163 



while all the Dinosauria, except Ceratosaurus, have these bones sepa- 

 rate. The exception in each case brings the two classes near together 

 at this point, and their close affinity has new been clearly demonstrated. 



RESTORATION OF CERATOSAURUS. 

 Plate XIV. 

 The, restoration of Ceratosaurus on PI. XIV represents the reptile one- 

 thirtieth natural size, and in a position it must have frequently assumed. 



ALLOSAURUS. 



Of the other carnivorous dinosaurs of the American Jurassic, three 

 genera, Allosaurus,Creosaurus, and Labrosaurus, are especially worthy 

 of notice. All were represented by species of large size, the natural 

 enemies of the gigantic herbivorous forms that were so abundant in the 

 same period. All had i>owerful jaws, sharp, cutting teeth, and a flexible 

 neck. The fore limbs were quite small, and the feet were armed with 

 strong claws for seizing living prey. The hind limbs were large and 

 strong, and the animals used them alone in ordinary locomotion. These 

 three genera maybe separated by distinctive characters, and it is proba- 

 ble that they were not all contemporaneous. 



The genus Allosaurus contains the largest carnivorous dinosaurs 

 known. It may be readily distinguished from Ceratosaurus by the ver- 

 tebra; and the pelvis, or the feet. 1 The cervicals are opisthocoelian in- 

 stead of plano-concave, and the pelvic bones and metatarsals are free, as 

 shown in Pis. X and XI. In Creosaurus, a smaller allied form, the teeth 

 in the premaxillaries are more numerous, while the sacrum contains 

 fewer vertebra? (PI. XII). Labrosaurus is evidently a quite different 

 type, for the dentary bone is edentulous in front, as shown in PI. XIII. 



EUROPEAN THEROPODA. 



From the Jurassic of Europe the best-known carnivorous form is 

 Megalosaurus, so named by Buckland, in 1824, the type specimen hav- 

 ing been found in England, near Oxford. Although the first genus of 

 dinosaurs described, but little has been made out in regard to the 

 structure of the skull, and many portions of the skeleton remain to be 

 determined. Its nearest American representative is probably Allosau- 

 rus, and both genera include species of large size. 



The most interesting member of the Theropoda known in Europe is 

 the diminutive specimen described by Wagner, in 1861, as Compsogna- 

 thus longipes. The type specimen, the only one known, is from the 

 lithographic slates of Solenhofen, Bavaria, and is now preserved in the 

 museum in Munich. Fortunately, the skull and nearly all the skeleton 

 are preserved, and as the specimen has been studied by many anato- 

 mists its more important characters have been made out. It is regarded 

 as representing a distinct suborder, and no nearly related forms are 

 known in Europe. A restoration in outline of this interesting dinosaur 

 has been prepared by the writer, and will be found on PI. LXXXI1. 



' The skull of Allosaurus ferox Marsh has an aperture in the maxillary in front of the autorlntal 

 opening. This apertnre is not present iji Ceratosaurus 



