456 Reptilian Epiphyses 
article for the forms discussed here. In addition to the forms there men- 
tioned I have recently examined the skeletons of two specimens of A mbly- 
rhynchus cristatus Gray, of the family Iguanidae, from the Gallapagos 
Islands; one specimen of Hremias pulchella Gray, of the family Lacer- 
tidae, from Africa; and a skeleton of a young Varanus, of the family 
Varanidae. 
In the embryos of Cnemidophorus sexlineatus Linné there are no 
epiphysial ossifications. In three young specimens of Sceloporus chry- 
sosticus Cope, 24 mm. in length from the tip of the snout to the base of 
the tail, which are two days old, the epiphyses can be detected as minute 
points in the cartilaginous pads at the upper and lower ends of the 
humerus and femur, and at the distal ends of the metacarpals and meta- 
tarsals. In a slightly older specimen of Sceloporus there have appeared 
at the distal end of the humerus four epiphysial centers. It is not at all 
unusual for more than one center to appear at the end of a long bone. 
On the humerus of Phrynosoma there are two centers on the distal end, 
and on the upper and lower ends of the humerus of Amblyrhynchus there 
are four and five centers respectively. In an adult specimen of Sceloporus 
the epiphyses have become almost indistinguishably united with the dia- 
physes. In this specimen, also, there appears the ununited olecranon, 
which was not apparent in the young. The olecranon in the lizards is of 
separate origin from the diaphysis and only unites with it late in hfe. In 
his paper on “ Traction Epiphyses” Parsons has figured the developing 
olecranon of Jguana and discusses its probable origin and its homologue 
in the higher vertebrates. 
In the young specimen of Phrynosoma, 26 mm. in length, there can be 
detected at the distal end of the humerus two epiphysial centers and one 
on the proximal end. One epiphysis is present on the distal end of all of 
the metacarpals. There are no epiphyses either on the radius, ulna, car- 
pals or phalanges. One epiphysis is present on the upper and one on the 
lower end of the femur. As in the fore hmb, there are no epiphyses 
present on any of the other bones of the leg, but epiphyses are present on 
the distal end of the metatarsals. In the adult specimen of Phrynosoma, 
46 mm. in length, the epiphyses are almost indistinguishably united with 
the diaphyses. The olecranon has not, however, joined the ulna. 
In the young specimen of Iguana, 73 mm. in length, there is one 
epiphysial center at each end of the humerus, one on each end of the ulna, 
none on the radius (Fig. 24). One epiphysis is present on each end of 
the femur, tibia and fibula, and one at the distal end of all of the meta- 
carpals and metatarsals. There are no apparent epiphysial structures 
