PELVIC AECH OF HESPEROKN1S. 75 



The neural spines of the sacral vertebrae, and of the others coossified 

 with them, are compressed transversely. AVith the exception of those of 



the two last, or urosacral, vertebra?, these spines do not extend above the 



upper margins of the ilia. These vertebrae are the longest of the series, 

 surpassing in extent even the anterior ones. 



. Some of the principal dimensions of the pelvic arch of Hesperornis 

 regalis are given in the measurements which follow : 



Measurements of Pelvic Arch. (No. 1206.) 



Length of ilium, 380.0 mra 



Depth of pelvis, across acetabulum, 74.0 



Greatest depth of ilium, behind acetabulum, 52.0 



Distance from anterior end of ilium to center of acetabulum, 104.0 



Transverse diameter of acetabulum, 24.0 



Total extent of coossified sacral vertebras, 320.0 



Length of the first sacral, or twenty-fourth, vertebra, 21.0 



Transverse diameter of anterior articulation, 25.0 



Vertical diameter of anterior articulation, 14.0 



Length of ischium from posterior border of acetabulum, 260.0 



Length of pubis and post-pubis, 330.0 



Extent of pubis in front of anterior border of acetabulum, 15.0 



Extent of post-pubis behind posterior border of acetabulum, 291.0 



Vertical diameter of post-pubis, at base, 12.0 



Greatest diameter of foramen in acetabulum, 12.0 



Least diameter of foramen in acetabulum, 7.0 



Height of anti-trochanter above acetabulum, 25.0 



Antero-posterior extent of anti-trochanter, 22.0 



Greatest distance between upper margins of anti-trochanters, 54.0 



Measurements of Twenty-fourth Vertebra. (No. 1477.) 



Length of centrum, 22.0 mm 



Least transverse diameter of centrum, 12.0 



Transverse diameter of anterior articulation of centrum, . . . 31.0 



Vertical diameters of anterior articulation of centrum, 11.0-1 7.0 



Transverse diameters of posterior articulation of centrum, 20.5-24.0 



Vertical diameter of posterior articulation of centrum, 12.0 



Transverse diameter of vertebra, across pre-zygapophyses, 20.0 



Transverse diameter of vertebra, across diapophyses, 52.0 



Diameters of pre-zygapophyses, 7.5-10.5 



Length of floor of neural canal, 20.5 



