Mbebiam.] 



New Ichthyosauria. 



257 



other. One or two additional ossicles may have been present in 

 this row but a careful search has failed to reveal them. 



Excepting phalanx one of digit two and two very minute 

 rounded ossicles at the distal end of the paddle, all of the 

 phalanges are sharply notched. Half of the phalanges in digits 

 one and three are notched on both sides; the remaining ones are 

 cut in on the outer border only. In digit two the notching is, 

 for some unknown reason, always on the posterior side of the 

 phalanges. The presence of the double notching on many of the 

 phalanges, occurring as it docs with greater axial length than is 

 found in these elements in the later groups of the Ichthyosauria, 

 can hardly be interpreted otherwise than as an indication that 

 • the phalanges were originally even longer than we find them 

 here and that their middle or shaft portions were considerably 

 constricted as in the normal phalanx of a shore or land reptile. 



Measurements. 



Humerus 



Length 61 mm . 



Width at proximal end 34 



Width at distal end 41 



Width at notch 22 



Thickness through pectoral ridge 20 



Radius 



Greatest length 31 



Width, proximal and distal 20 



Width, median 16.5 



Ulna 



Greatest length 31 



Width, proximal and distal 20.5 



Width, median 18 



Radiale 



Length. 15 



Width 14.5 



Distal carpal one, length 11.5 



Metacarpal one, length 10 



Posterior limbs (PI. 22, fig. 2). — The posterior limb is much 

 smaller than the anterior, the parts present indicating that its 

 total length was about one-third shorter. This paddle is also of 

 the tridactyle type but the fourth digit is a little larger than that 

 indicated in the anterior limb. The femur is much smaller than 

 the humerus and has a much more slender median or shaft 

 region. The tibia and fibula were both considerably longer thau 



