1893 - 94 .] Professor Ewart on Digits in the Horse. 187 
Vestigial structures are generally supposed to reach their maxi- 
mum development early, and then to either degenerate or dis- 
appear. From the material already examined, it seems the second 
and fourth digits reach their highest development when the embryo 
is from 30 cm. to 40 cm. in length. For example, in an embryo 
35 cm. in length the second and fourth digits were remarkably 
complete. Including the metacarpals, they varied in length from 
3-2 to 3*5 cm. — the phalangeal portions varying from 3 to 4 mm. 
