HATCHER: OSTEOLOGY OF HAPLOCANTHOSAURUS 43 
scapula at the proximal end is 372 mm., at the distal ® 396 mm. and in the middle 
only 137 mm. Between the spine and the coraco-scapular suture there is a broad 
but shallow cavity on the external surface of the scapula. Above this ridge, how- 
ever, the external surface of the scapula is convex in all directions. The total length 
of the scapula from its superior or proximal end to the coraco-scapular suture is 800 
mm. The accompanying figures show very well the form and principal characters 
of this element. 
From the foregoing description of the types of the two species of Haplocanthosau- 
rus at present known and from the accompanying measurements and figures it will 
appear that as compared with Diplodocus the present genus was represented by 
animals with the thorax somewhat more elongated and with neck and tail relatively 
shorter than those which obtained in representatives of the former genus. While, 
judging from the femur, the only element of the limbs at present available, the ap- 
pendicular skeleton was relatively strong when compared with the axial. 
Distinctive Generic Characters. 
The principal characters distinguishing the genus Haplocanthosawrus may be 
summarized as follows : 
Frrsv. — Neural spines short and simple (not branched) throughout the entire verte- 
bral column. 
Second. — Newral spines of the anterior sacrals codssified, forming an elongated bony 
plate. 
Turrp. — Height of newral arches in posterior dorsals exceeding length of neural 
spines. 
Fourtu. — Transverse processes of the anterior and mid-dorsal regions inclined wp- 
ward and outward instead of directly outward. 
The two species described above may be distinguished as follows by their respec- 
tive sacra. 
HAPLocANTHOSAURUS PRISCUS. — With newral spines of the three anterior sacrals 
coossified, those of the two posterior remarnung free. 
HAPLOCANTHOSAURUS UTTERBACKI. — With newral spines of the fowr anterior sac- 
rals coossified throughout their entire length and with that of the fifth sacral at the top and 
bottom. 
Taxonomy. 
All systematists will, I think, agree with me in placing the present genus 
y ) p ENS § 8 
among the Sauwropoda. The scapula, coracoid, pelvis and sacrum, as well as the 
presence of large pleurocentral cavities in the presacral centra, together furnish 
°T consider that end of the scapula which opposes the humerus as the distal. 
