STRUCTURE AND RELATIONSHIPS OF OPISTHOCELIAN DINOSAURS. 241 
of its entire length below the great trochanter. A marked rugosity, 
probably for the insertion of one of the gluteal muscles, extends down- 
ward from the great trochanter to this point. As in all opisthoccelians 
the fourth trochanter forms a rugose prominence on the posterior 
internal margin of the shaft above the middle. 
MEASUREMENTS OF THE LEG BONES. M. 
eee itt hy Of DATallel tra MiSs. ta. id aaa alah d et ee gk Cava ete Hn aha. s 2.04 
Beemer breadth OL PrOXiAnenG, Wed set ities wots as ale boa dla es 65 
Mumenwess Of head antero-posteriorly + .0.6 Ge a lek we ns .28 
Seen tN .OF WUCCLe SMaArL aus ot tie ile Sulele Gea). alo tae eae ow 24 
Distance from angle of great tuberosity to upper margin of deltoid 
TS CRI iets a Me 700 ON ie Np Nee Ace Oe ee PLS: 
eee TL DATALEL GQ AXIS 3 Yi Mme Orel tls uae ayes Ea asta seus ed 4103 
Pee OR CAC And POTeCAL (LOCDAN CET 4 aul aif. i8epclsi am Wes a eee we 8 .59 
Servo sart at Tourin trocianver.... ie ck otc Se tp ee Te ce M42 
Sim PATIGLAL CHG osc. sta ta he chatted ete eee he ees ee es .58 
‘ Distance from head to upper margin of fourth trochanter........ My 2 
PEPE iest TEAC CH a) She ate ter es, oA iin detetg WB PA eal deca gees .87 
MemeerenOroer to scalpular mMarginc.\.. 1%, pelagic aca yee ek .54 
BeINRTECEIAT OID AL TOTAII ETI, gin 2 Sew aly ae as BUN oak wie Let 8 ate ss 34 
REC CCTIQ GIL Gr 0) yi tet tec alles o.b,3% Se eR etn oe ln a bd ede es 1.24 
Serer DTEACetAOtuAT PIAte seid. 5) ype oie odie ae De we 33 
Mrssesieoreat peduncle to anterior’ angle. (i... 2s he. ee oe .40 
PRIME PUES ECT Lee 5 la cosa ture We hake: ob «Mee aa ve ae Loses ha woe Goi“ 
muevemaceratnium. (Estimated). 3... sw uaa. ae wll dee be 45 
Lateral breadth of acetabular wall ............... ehh ae eee ag 
fegeenecs orate atiantero-inferior angles. 2.2... ee ae ee. .08 
PnenMess Or Crest above. Ppreat peduncles: .) da dent de 6 ease wees .025 
Bememstieeeen  OcteriOe anys. io. A cick is ee buBaaiie 4s we 4 ap: 
RELATIONSHIPS. 
In proposing the genus Brachitosaurus from the characters pre- 
sented by the leg bones and sacral centra of this specimen, the writer 
had some doubt as to the possible relations with the imperfectly 
described genus Camarasaurus. However, a recent examination, 
through the courtesy of Dr. Osborn, of the type specimen as it is 
being prepared for exhibition in the American Museum, at once set 
at rest all such doubts. The massive structure of the vertebre and 
the distinctly Morosaur-like spines of that genus have nothing in 
common with the slenderly constructed and elongate centrum and 
the single median spines of Brachiosaurus. Relationship with the 
tall and slender posterior dorsal vertebra which constitutes the type 
of Amplucelias is equally impossible. 
Of all the American opisthoccelia the only known form which 
may be regarded as closely related to this genus is Haplocantho- 
