XECT. L] LAEVIFORM EMBRYO OF THE MOLE. 15 



Know one, know all; one diagram would represent 

 all, one description serve for all. 



Such a stage, moreover, gives us a form extremely 

 like that of any other gill-less type bird or reptile ; 

 while to make it into a semblance of the lower aquatic 

 types, more "visceral arches," with more and more 

 gaping clefts, are all that would have to be added. 



In all we have the curved, larviform creature, with its 



FIG. 1. Embryo of Mole (Talpa europcea, 1st stage), 

 magnified 12 diameters. 



large brain-lobes bent under, in front ; its tail-end bent 

 under, behind; its solid front folds, its rudimentary gill- 

 openings, and its paddle-shaped limb-buds. But the 

 characters derived from its more immediate ancestry 

 soon show themselves. By the time the gaps in the 

 throat are filled up, and the embryo has doubled its 



