HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDEA. 327 
MEAsuREMENTS (No. 1604). 
Length of eighth right rib. Measured in a straight line................... 664 
Diameter of upper portion including head......................-5-.-0-5. 66 
Greatest diameter of shaft near the middle.................-.--+2+--00-. 35 
Greatest diameter olshatt meaty ends me meen eee asain ciao ees 44 
The Ninth Rib. 
The ninth rib is shorter than its predecessor; the bone is very much reduced 
in all its diameters from those that precede it and shows a tendency throughout 
to become more oval in cross-section. The angle on this rib is further removed 
distally from the capitulum than in any of the ribs preceding or succeeding it 
and is followed by a flattened depressed surface externally. 
Measurements (No. 1604). 
Mm 
Length of ninth right rib. Measured in a straight line.................... 634 
Diameteromupperportionuncluding headeney ss ee ses saa snc sc eros 67 
Greatest diameter of shaft near the middle,........................-..-. 29 
Greatesidiametemomshatimeanendy syn are yer aatermcn sca deee oe: 37 
The Tenth Rib. 
The tenth rib is considerably shorter than its predecessor. Its antero-posterior 
diameter is less than in any of the ribs preceding it. The angle retreats toward 
the capitulum and is followed distally by a flattened excavated surface. In cross- 
section throughout the greater part of its length the bone is approximately oval. 
Measurements (No. 1604). 
Mm 
Length of tenth right rib. Measured in a straight line.................... 605 
Diameter omupper portiomineluding heads. - 2 ssc de ee eos oe 60 
Greatest diameter of shaft near the middle..................... Be cee: 25 
Greatestdiametemor shattmeanende marries: decries ia edie 32 
The Eleventh Rab. 
The eleventh rib is shorter than the tenth, somewhat lighter; a deep groove 
runs along its posterior face from the capitulum to beyond its middle. Its anterior 
surface is strongly convex. The angle is situated at about the same distance from 
the capitulum as in its predecessor, and, like it, followed distally by a flattened 
somewhat excavated surface. The rib in cross-section is very irregular at different 
points, but toward its extremity shows a tendency to become rotund. 
