rKOTOSTEGIDJE. 



I 9 I 



The specimen of this species which Cope originally described was found bv him in 1 871, 

 m Niobrara deposits, near Butte Creek, south of Wallace, Kansas. This is now in the Ameri- 

 can Museum of Natural Historv and has the number 1503. At the time of its discovery the 

 bones were much distorted and comprest; and most of them were much fractured in collecting 

 them. Cope states that the portions described bv him were reconstructed out of over 800 

 pieces. One of the large bony plates, described as overlying the ribs, had been broken into 

 108 pieces. Most of the bones are vet in the condition in which Cope left them; the large 

 plates are, to a great extent, again broken up. 



\s stated by Cope, the remains preserved include many parts of the skull; 5 vertebra?, 

 more or less incomplete; the scapular arches of both sides, with the coracoids; both humeri 

 perfect, and some phalanges; 10 ribs; 1 doubtful neural bone; 10 peripherals; parts of 4 

 large plates, described as overlying the ribs; and some undetermined bones. 



From his study of his materials Cope arrived at the conclusion that Protostega was a 

 large marine-turtle closely allied to Dermochelys, and had a total length of about 12 feet. 



The first author who added to the knowledge of the species was Dr. George Baur, who 

 (Zool. Anzeiger, ix, 1886, p. 688), regarding the genus as Atlantochelys, stated that the plates 

 assigned by Cope to the dorsal region were really portions of the plastron. This determination 

 was undoubtedly made from the bones collected by Cope. Hay, as cited, gave, in 1897, a 



FlG. 247. Protostega gigas. Skull of type. 



Xj- 



Cope's determinations of the bones within parentheses, ju (pt), jugal, Cope's pterygoid : mx (por), maxilla. 

 called by Cope the postorbital; prf, prefrontal; pof, postfrontal; quj {col), quadratojugal, Cope's columella; 

 sq (inx), squamosal, called bv Cope maxilla. 



description, with figures, of the hyoplastra and hypoplastra of a specimen that had been 

 collected for him near Butte Creek. Kansas. Case (1897, as cited) described portions of the 

 skull and a more complete plastron than had previously been secured, materials now in the 

 University of Kansas; and made correction of Hay's restoration of the xiphiplastra. More 

 recently Wieland has described excellent materials which belong to the Carnegie Museum, 

 at Pittsburg. 



Cope had considerable portions of the skull and most of these he figured. The writer 

 has studied these bones and has found that in most cases Cope's determinations were incorrect. 

 Baur had also examined these cranial bones and accepted Cope's determinations (Amer. 

 Naturalist, XXIV, 1890, p. 532). 



Fig. 247 represents these bones, each having its name indicated. Cope's determinations 

 are indicated in parentheses. 



The first of these elements that will be noticed is that which Cope called the postfrontal 

 I Vert. Cret. Form. West, plate xi, figs. 3a, 36). In his description he called this the left post- 

 frontal; but, since the straight margin was regarded as the lower, the bone would have to be 

 placed on the right side. In reality, the bone is the left maxilla (fig. 247, mx), joined to the 

 prefrontal. The straight border is the cutting-border of the maxilla; and the crusht tritu- 

 rating surface is seen, in Cope's figure, pushed below this border. Evidently the cutting- 



