572 
The figures shows that the two specimens are strikingly similar. 
The chief differences can be easily stated. (For convenience I shall 
call SzAwLOwskKrs A and mine B.) 
A is a 24th vertebra, B is probably a 25th. The foramen is 
larger in B and apparently more oval. In A the greatest diameter 
is 6 mm; in B it is 10 mm, the smaller being 7 mm. In A the 
bone before the foramen is much smaller in a vertical direction than 
behind it; in B the front piece is a little the larger (2 mm). The 
left transverse process is normal in A; it is too broad in B. The 
costal element is more transversely disposed in B, and has perhaps 
a more striking superficial resemblance to a rib. 
They are, in my opinion, instances of imperfect differentiation 
of the costal element. 
Harvard Medical School, Boston, January 3, 1902. 
Nachdruck verboten. 
Wodurch unterscheiden sich die jungen Embryonen des Straußes 
von denen anderer Vögel? 
Berichtigung von Paut MirropHanow in Warschau. 
In der soeben erschienenen zweiten Lieferung des „Handbuches 
der vergleichenden und experimentellen Entwickelungslehre der Wirbel- 
