Marsh — Restorations of Claosaurus and Ceratosaurus. 345 



The main characters of the vertebral column of Claosaurus 

 are well shown in the restoration. There are thirty vertebrae 

 between the skull and sacrum, nine in the sacrum, and 

 about sixty in the tail. The whole vertebral column was 

 found in position except the terminal caudals, which are here 

 represented in outline. The cervical vertebrae are strongly 

 opisthoccelian, and the first eleven have short ribs. The 

 dorsals are also opisthoccelian. There are no true lumbar 

 vertebrae, as the last of those in front of the sacrum support 

 free ribs. The anterior caudals are opisthoccelian. The first 

 and second have no chevrons. Behind these, the chevron 

 bones are very long, indicating a powerful, compressed tail, 

 well adapted for swimming. 



In the median dorsal region, between the ribs and the 

 neural spines, are numerous rod-like ossified tendons, which 

 increase in number in the sacral region and along the base of 

 the tail, and then gradually diminish in number and size, 

 ending at about the thirty-fifth caudal. These ossified tendons 

 are well shown in the restoration, and are of much interest. 

 They are not unlike those in Iguanodon described by Dollo, 

 but as a rule are more elongate, and appear to lack the definite 

 arrangement in rhomboidal figures observed in that genus.* 



The fore limbs are unusually small in comparison with the 

 posterior, and the relative size of the two is well shown in 

 the restoration. The scapular arch presents many points of 

 interest. The scapula is large, and so much curved that its 

 shaft is nearly at right angles to the articular faces of its lower 

 extremity. On the anterior margin, above the articulation for 

 the coracoid, is a strong protuberance, with a well-defined facet, 

 adapted to -the support of the clavicle, if such a bone were 

 present. The coracoid is very small, and is perforated by a 

 large foramen. The two peculiar bones now generally re- 

 garded as belonging to the sternum were not coossified. 



The humerus is comparatively short. The radius and ulna 

 are much elongated, the latter being longer than the humerus, 

 and the radius about the same length. The ulna has a 

 prominent olecranon process, and is a stouter bone than the 

 radius. The carpal bones were quite short, and appear to have 

 been only imperfectly ossified. The fore foot, or manus, was 

 very long, and contained three functional digits only. The 

 first digit was rudimentary, the second and third were nearly 

 ecpal in length, the fourth was shorter and less developed, and 

 the fifth entirely wanting, as shown in Plate VI. 



In the functional digits (II, III, IY), the phalanges are 

 elongate, thus materially lengthening the fore foot. The ter- 

 minal phalanges of these digits are broad and flat, showing 



* Archives de Biologie, tome vii, p. 249, Gand, 1886. 



