ANATOMY OF A MONODACTYLOUS FOETUS 393 



is a well marked metacarpal ossification, and at right angles 

 to this and lying in the narrow digital part of the appendage 

 is the ossification representing the first phalanx. In the region 

 of the second phalanx there is yet no bone, while the distal 

 phalanx is represented by an extremely small centre of ossification. 



Some delay is thus evident in the processes of ossification in 

 these limbs since the appearance of the primary center in a meta- 

 carpal is usually in the ninth week and for a middle phalanx 

 about the twelfth week, (Keibel and Mall.) 



The skeleton of the lower limb (fig. 5) appears to be normal 

 except that no middle phalanges yet show ossification. Meta- 

 tarsals, proximal and distal phalanges are all ossified as are 

 also the talus and calcaneus. The long bones are normal. 

 Delay in ossification in the middle phalanges is again evident in 

 these limbs. 



The skull shows no abnormalities, although ossification is 

 very heavy in the base, especially in the petrous regions and 

 body of the sphenoid, but the vertebral column and ribs show 

 some interesting features. The vertebral body (fig. 6) shows 

 as a transversely oval patch with a small clear spot in the center, 

 indicating the position of the notochord. The appearance of 

 the body indicates the occurrence of ossification from bilateral 

 centers or else from a center indicating a bilateral origin. The 

 ossified part of the neural arch is still divided into its two halves, 

 no fusion having yet occurred either with the bodies or dorsal 

 to the spinal cord. The center in each half of the arch (fig. 5) 

 is quite distinctly seen lying to the side of the body and on the 

 thoracic vertebrae well marked transverse processes can also be 

 seen. In the sacral region the centers for the neural arches are 

 very insignificant and none are to be seen for the coccyx. The 

 first three sacral vertebrae show a well marked center of ossifi- 

 cation (fig. 6) on each side in the lateral mass. There are seven 

 well marked cervical vertebrae, thirteen thoracic, five lumbar, 

 five sacral and one coccygeal. The first sacral may be identified 

 by the presence of the centers in its lateral masses, so that it is 

 evident that the presacral vertebrae are twenty-five in number 

 instead of the normal twenty-four. That the supernumary 



