No. 633] INHERITANCE IN THE OSTRICH 



295 



surface of the body. Examination of chicks from the 

 time of hatching onwards leaves no doubt that the pre- 

 natal callosities become those of the adult, the elevations 

 becoming larger and coarser with use. 



The rather insignificant callosities on the wing also 

 show themselves on unhatched and newly hatched chicks. 



They are hardly distinguishable by any special thicken- 

 ing of the skin, but by the appearance of a faint reticula- 

 tion in places corresponding with those in which they are 

 found in the adults, and which serves clearly to separate 

 them from the surrounding smooth surface. Even the 

 tip of the third digit where sufficiently projecting shows 

 a few markings, leaving no doubt they would later become 

 the functional callosity. 



