246 Prof. H. G. Seeley on the Ornithosaurian Pelvis. 



sists apparently of not more than three vertebrae The pubis 

 is partly crushed inward in the middle line and the pubic 

 bones converge forward. The ischium also appears to have 

 extended inward to the middle line of the vertebras. The 

 part of the ilium anterior to the acetabulum appears to be 

 thin and free from the vertebras ; the depth of this plate is 

 about T 3 o inch. The prepubic bones are preserved on both the 

 right and left sides ; that on the left side is l^j inch long, it 

 has a slender shaft for nearly an inch, and then expands like 

 a fan to a transverse width of l^V iuch ; this expanded part 

 is thin and rests upon the ilium. 



In Pterodactylus longirostris (Cuvier) the pubis is partly 

 obscured because the femur is preserved in situ. The ilium, 

 which is pointed and long anteriorly, short and truncated 

 posteriorly, is -g-f inch long. The vertical depth of the pelvic 

 bones is $$ inch. On the ventral border there is a slight 

 notch between the ischium and pubis, showing the latter to be 

 the smaller bone. The antero-posterior measurement over 

 these bones is -$r inch. The prepubic bone is relatively 

 large, gV inch long, and expands anteriorly in a fan form to 

 a transverse width of fV inch (fig. 4) . 



In Pterodactylus rhamphastinus (Wagner) the ilium extends 

 lfV inch in front of the femur. The prepubic bone is x 7 o inch 

 long and expands in a fan form at its free end. 



In Pterodactylus Koclii (Wagner) the pelvis is badly pre- 

 served. It has the prepubic bone widely expanded at its 

 free end. 



In Pterodactylus micronyx (v. Meyer) the ilium is spear- 

 shaped anteriorly. The ischium and pubis are displaced and 

 imperfect. The prepubic bones have the shaft slender and 

 long ; the expanded end is fan-shaped (figs. 5, 6). The bone 

 is fully yV inch long. 



In Pterodactylus medius (Miinster) the ilium is lj\, inch 

 long, of which one inch is anterior to the head of the femur. 

 The pubic and ischiac bones are well developed. The pre- 

 pubic bones have a fan shape, appear to be -fij inch long, and 

 about half an inch wide at the expanded end. 



These examples may be sufficient to show how slightly the 

 prepubic bone varies in type among the short-tailed animals 

 which comprise the suborder Pteiodactylia of de Blainville. 

 The prepubis is approximately one half the length of the 

 ilium in all the species. The small size of the specimens and 

 the nature of the matrix have not been favourable for 

 displaying the articular facet of the slender shaft; but in 

 every case the termination of the prepubic bone is a clean-cut 

 transverse line, and I have never observed any circumstance 



