460 O. C. Marsh—sStructure of Mosasauroid Reptiles. 
Lestosaurus gracilis, sp. nov. 
is nearly round, and larger than in any known species of the 
genus. The quadrate is likewise very characteristic. The m- 
ternal angle of the proximal end is much less than a right angle, 
although the great ala is nearly in the same plane as the outer 
margin of the hook. This leaves a deep broad notch between 
the alar process and the internal angle. There is a deep groove 
below the meatal pit. The distal articular face is convex in 118 
longer direction, but concave antero-posteriorly, owing to 4 
shallow depression which divides the inner third from the outer 
ortion. The lower margin of the ala extends inward near! 
Paatatly, and is produced into a compressed process, whie 
meets the free end of the hook. The borders of the articular 
surfaces are strongly striated. 
The articular ends of the cervical and dorsal vertebra ate 
transversely oval, with a distinct excavation on the superior 
r; 
neural canal, between the anterior zygapophyses, ‘des of 
species, but there is no groove between these and the sides 
the roof. The zygantral excavations are well marked. 
Measurements. hae 
Length of parietal on median line,.............0099 fed 
Width in tron, cic: cas <a, (Kk ENE OO ike ~~ 
Antero-posterior diameter of parietal foramen, ...-+++*+* bs 
Pransyerse. diameter, . oi 5.0500 s ences = gkeamess eeeee a 
Length of qua oe Ska ough ee at ae act ; nani ee ie 
Length of posterior hook,...-...-..0cisevreeenrscst? ott 
Transverse diameter of distal articular face,....---°> ian fe 
Antero-posterior diameter, .........2-+e0e2+00000" ae 
Length of centrum of axis,............---- AP ae ee 
Height of neural spine of axis above floor of neural ca pean : 
Ante . a 
