176 r DtNOSAttKIA. 



Family OMOSAUHID^E. 



Cranium (fig. 31) typically elongated, low, and narrow anteriorly, 

 with large orbits, low infratemporal fossae, and moderate nares ; 

 mandibular rami rather shallow, with narrow symphysis terminated 

 by a predentary bone. Teeth scelidosauroid. Vertebras amphi- 

 coelous ; dorsals with slight lateral depressions on centrum, very 

 narrow neural canal, and lofty arch without deep pits in front of 

 postzygapophyses ; each sacral bearing entirely or partly its own 

 arch ; anterior caudals with transverse diameter of centrum longer 

 than vertical ; chevrons open ; rib-facets of middle dorsal vertebrae 

 on arch. Limb-bones solid ; scapula (fig. 32) with large glenoidal 

 expansion, forming a right angle with anterior border of shaft; 

 coracoid without descending process : humerus short and thick, with 

 expanded extremities. Ilium (fig. 32) with very long and stout 



Fig. 31. 



s, Marsh. — Left lateral view of cranium ; from the Upper 

 Jurassic of North America. \. a, nares ; b, orbit ; c, infratemporal fossa ; 

 pm, premaxilla ; m, maxilla ; n, nasal ; pf, prefrontal ; so, supraorbital ] ; 

 fp, postfrontal ; po, postorbital; I, lachrymal; j, jugal; g, quadrate; sq, 

 squamosal ; oc, occipital condyle ; ar, articular ; sa, surangular ; an, 

 angular ; s, splenial ; d, dentary ; pd, predentary. (From the ' Amer. 

 Journ.') 



preacetabular, and short postacetabular process ; pubis and ischium 

 short, without distal expansion ; femur with or without distinct inner 

 trochanter, much longer than tibia, which is not greatly longer than 



1 This bone, forming the upper border of the orbit and connecting the pre- 

 and post-frontals, appears to be an element usually not represented as a distinct 

 bone. 



