WILLIS JON AND CASE: KANSAS MOSASAURS. 25 



expanded at the proximal end. The greatest convexity is shown about 

 the middle of the series, where the versedsine of the curvature is forty 

 millimeters, the chord being one hundred and sixty. Posteriorly, the 

 short ribs are only gently curved. 



Lying by the side of the vertebral column, and between the ribs, as 

 they have been pressed down, are a number of flattened, soft, punctu- 

 late bones, which are evidently the costal cartilages. Posteriorly four 

 rows of them are seen, lying closely side by side, some of them eight 

 or ten inches in length. The sternum, composed of the same material, 

 has been so crushed and crumpled that its shape cannot be made out. 

 The whole structure here, whether of ribs, cartilages or sternum, 

 reminds one very strongly of such lizards as the Iguana or Monitor. 

 There is no indication, however, in any specimen, of an episternum. 



MEASUREMENTS OF RIBS. 



Length, first thoracic rib, (chord) 200 millim. 



Length, eleventh thoracic rib, (chord) 145 



Length, thirteenth dorsal rib 68 



Length, eighteenth dorsal rib 64 



Length, thirty-fourth dorsal rib 52 



The lengths of the different regions, as they lie in their natural 



relations, are as follows : 



Skull 0.420 meters. 



Neck 0.225 



Trunk , 1-360 



Tail 1 . 460 



Total 3-465 1 1 ft. 7 in. 



The measurements of an excellent specimen of C. tortor are as 



follows : 



Skull o. 630 meters. 



Neck o. 360 



Trunk, (thirty-three vertebrae preserved) 2.370 



A very complete specimen of a Liodon in the Museum, in which the 



complete vertebral column is present, numbering one hundred and 



seventeen vertebrae, gives the following measurements. The skull is 



complete, save the most anterior portion. 



Skull (approximated within narrow limits)'. . . o. 700 meters. 



Neck o. 430 



Trunk i. 760 



Tail „ 3.420 



Total 6.310. ... 20 ft. 8 in. 



The vertebral series in this specimen is composed of seven cervicals, 

 twenty-three dorsals, seven pygials, and eighty chevron-caudals. 



