2o8 



THE DOCTRINE OF DESCENT. 



discovery of Fritz Miiller's that a shrimp (Peneus) still 

 begins its development as a Nauplius ; whereas all the 

 other members of the order, as far as they are known, 

 leave the egg in the higher Zoea phase (p. 50). As of 

 the hundreds of stalk-eyed crabs, scarcely a dozen have 

 been hitherto examined as to their development, it 

 will not be doubted that, with regard to the Nauplius 

 phase, some resemble the Peneus of the Brazilian coast. 

 But even were this case to prove unique in the order, 

 it would suffice as a living witness of the connection 



Fig. 17. Axoiotl. 



between the presence of the decapods and the primor- 

 dial crabs. There can be no other view of this subject. 

 The Nauplius phase in the development of the Peneus 

 is either a shining testimony in favour of the doctrine 

 of Descent, or a senseless paradox. 



