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A REVISION OF THE COTYLOSAURIA OF NORTH AMERICA 



the closed mouth these teeth, or the inner ones, protrude quite a distance below the 

 mandible, hook-like or rake-like, as shown in plate 12, fig. 4 (of this paper). This 

 extraordinary development of these teeth and their position, in association with the 

 narrow, compressed facial rostrum, remind one strongly of the phytosaurs and are 

 suggestive of like habits in the living creatures; the exhumation of burrowing inver- 

 tebrates from the mud or sand of the shores or shallow water. The maxillae, free in 

 one of our specimens, are rather slender bones, with their greatest width a little in 

 advance of the orbits. They extend back, decreasing in width, to nearly opposite 

 the posterior part of the orbits, uniting above in front with the elongated lachrymals, 

 behind with the anterior prolongation of the jugals. 



"I count in different specimens seventeen teeth, not very different in size, the 

 longest a little in front of the middle of the series, and the series separated from the 

 outermost of the premaxillary teeth by a short diastema. The nasals form the upper 

 side of the rostrum as far as their union with the frontals, a little in advance of the 

 orbits, cumng a little downward on the sides back of the nares, whose upper borders, 

 only, do they form. The prefrontals are subtriangular in shape and small; their 



Fig. 46. — Labidotauru!. One of the specimens on which Copt based the genus. X J. No. 4414 Am.Mus. 

 Oy top Tiew, no sutures shown; b^ side view of a; c, diagram of top of skull showing probable position of sutures. Lettering as usual. 



inner sutures begin a little beyond the middle of the upper orbital margin and are 

 parallel with each other, extending a little beyond the end of the frontal bones. The 

 lachrymals are large bones, united broadly with the nasals, anterior to the prefront- 

 als, and with more than half the length of the maxillae below. They form the 

 posterior boundary of the nares and the larger part of the anterior border of the 

 orbits. The precise boundary between the nasals and lachrymals may be somewhat 

 indefinite; the sutural line given is that in which four skulls seem to agree. The 

 frontal bones have nearly parallel sides, extending posteriorly a little beyond the 

 hind margins of the orbits, joining the parietals in a transverse serrate suture, which 

 appears on the under side somewhat in advance of the line above. The frontals 

 form but a small part of the upper orbital margin. The postfrontals are also small, 

 forming the posterior upper margin of the orbit, and leaving but a small space of 

 frontal margin between them and the prefrontals. The postorbitals are larger than 

 the postfrontals, and also extend a little further back of the frontal suture. They 

 form most of the hind border of the orbits, articulating with the squamosal behind 

 and the jugal below. The jugals begin a little in front of the middle of the orbit in 

 an acute point between the lachrymals and the maxilla. They are broader just 

 behind the orbit, where they articulate with the postorbitals above and the squamosal 



