GILMORE: OSTEOLOGY OF BAPTANODON (MARSH) 89 
narrower antero-posteriorly than laterally and concave on the inner border where 
it meets the descending process of the pterygoid. 
MEASUREMENTS. 
No. 878. Greatest length of the quadrate.............2...-.eseceecoeseeeeeseeeeeees 
HO zs) ‘width distal end of the quadrate 
ce 603. “e “e oe “ “ ce 
** 878. te ‘“ antero-posteriorly of the quadrate 43‘ 
“603. se i £ GG es COT) AAS at sciee penne 40 ‘ 
Quadratojugal (q.j.).— The quadratojugal seen from the side is a small triangular 
bone that connects the jugal and postorbital with the quadrate. The posterior 
border of this bone is slightly rounded ; distally somewhat expanded, thus forming 
an articular end which meets the outer border of the quadrate at nearly right angles, 
resting upon this edge just above the heavy articular end of the latter. 
The external surface is flat. The opposite side forms the outer boundary of the 
foramen at this point. Superiorly this element passes under the quadrate and 
supratemporal, the upper portion being hidden from a side view by the overlying 
postorbital. The infero-anterior border is united with the jugal by a suture 47 mm. 
long. The lower border of this bone is 57 mm. in length. 
Postorbital ( pto.)—The postorbital is a more slender element than the jugal, and 
as Owen” has observed ‘‘ resembles a dismemberment of an ascending process of the 
malar.” Its lower end overlaps and joins by squamous suture the posterior end 
of the jugal. This suture between the jugal and postorbital is 89 mm. in length, 
the same as given by Professor Seeley for the corresponding suture in Ichthyosawrus 
(zelandicus) quadriscissus.” As it rises to the middle of the back of the orbit the 
width remains about the same, above the middle it curves upward and forward along 
the lower margins of the supratemporal and postfrontal. Above the middle of the 
orbit the postorbital suddenly expands, then tapers to a slender point that termi- 
nates on the lower border of the postfrontal nearly at the top of the orbit. Viewed 
laterally the surface is slightly concave. The anterior border forms the posterior 
boundary of the orbit. This bone unites with the jugal, quadratojugal, supra- 
temporal and postfrontal. 
Sclerotic plates (scl.).—'The sclerotic ring is unusally well preserved in at least 
one orbit of both skulls. In No. 878 the ring is composed of fourteen wedge- 
like plates, the inner ends being truncated by the pupillary opening. 
From the pupillary border the plates extend outward ray-like to the periphery 
of the eyeball, there bending sharply inward completely enclosing the outer borders. 
2> Owen, R., lit. cit. 
“7 Seeley, H. G. Quart. Jour. Geol. Soc., of London, Vol. XXXVI. 
