46 



NEW REPTILES AND STEGOCEPHALIANS FROM 



posteriorly and broaden transversely through the sixth, seventh, and eighth rows, and 

 by the ninth they have reached the normal form of the dorsal series, which continues 

 back nearly to the sacral region. The low spine or knob is located a little outside of 

 the center and is directed backward and inward. The plates are covered by a rough 

 sculpture, shown in figure 18 c, which extends to the thin edges except for about 1 or 1.5 

 centimeters on the anterior edge. This smooth area on the edge of the plate indicates an 

 overlapping, but it must have been very slight in the dorsal region. Examination of the 

 plates in the armor of several species of alUgators, crocodiles, and caimans shows that there 

 is no, or very slight, overlapping of the plates in any of these forms, and that it occurs only 

 in an overflexion of the back. The same smooth area appears on some of the plates 

 in these Uving forms and seems to be a region of attachment of tough skin or tendinous 

 material. The outer plates have low, sharp spines, which are broader antero-posteriorly 

 in the sixth and seventh rows, but of nearly equal diameters in the ninth and following 

 ones. The spines were inclined outward and a little backward. The inner half of the 

 base is shorter than the outer. The inner half is nearly horizontal and the outer half is 

 nearly vertical, but inclined a little outward. There is evidence from one side or the 

 other of 17 plates of this kind, making at least 9 rows in the mid-dorsal series. 



Fig. 18. — Desmatosuchus spurensis. 



A. Median plate of a mid-dorsal series. X 0.3. 



B. Outer view of a lateral plate of a caudal series, left side. 



C. Posterior view of B. 



X0.3. 



Posterior to the plates of the dorsal series there are no representatives of the median 

 plates, but there is a considerable number of plates from the outer series. They differ 

 notably from those of the prepelvic region (fig. 18 b and c) . The outer half of the base is 

 much longer than the inner, and is in the same plane with the outer sides of the spines. 

 This character becomes more noticeable as the plates become smaller, that is, in the pos- 

 terior part of the caudal series. The spines are relatively higher than in the dorsal series. 

 The sculpture becomes less rough in the posterior plates. It is believed that in the 

 distal portion of the tail the median row disappeared, as it does in the Crocodilia. 



The scapula-coracoid.—With the skeleton was found the distal end of a scapula- 

 coracoid so radically different from the usual form found in the Phytosauria that it is 

 diflScult to reconcile it with the vertebral column, but it is no more peculiar than the skull. 

 It does, however, resemble very closely the scapula-coracoid of Stagonolepis. The 

 cotylus IS large and cleanly formed and is somewhat obliquely placed in the bone. The 

 upper edge overhangs strongly; the lower edge is broken away. A ridge interrupting 

 the smooth face of the articular surface is perhaps due to pressure, but seems normal. 

 Just anterior to the edge of the cotylus is a pit which seems to belong to the bone and 

 not due to the action of decay and gypsum. The coracoid foramen is at about the level 

 ot the lower edge of the cotylus and perforates the bone upward and inward; on the 

 postenor side the opening of the foramen is directly upward. On the anterior edge 



