SUCCESSION OF CHARACTERS. 269 



and have on that ground an influence in modifying the 

 form, may be recognized long before the ordinal charac- 

 ters are fully developed. The Snappiiig-Turtle, for in- 

 stance, exhibits its small crosslike sternum, its long tail, 

 its ferocious habits, even before it leaves the egg, before 

 it breathes through lungs, before its derm is ossified to 

 form a bony shield, etc. ; nay, it snaps with its gaping 

 jaws at any thing brought near, when it is still sur- 

 rounded by its amnios and allantois, and its yolk still 

 exceeds in bulk its whole body. 1 The calf assumes the 

 form of the bull before it bears the characteristics of the 

 hollow-horned Ruminants ; the fawn exhibits all the pecu- 

 liarities of its species before those of its family are un- 

 folded. 



With reference to generic characters, it may be said 

 that they are scarcely ever developed in any type of the 

 animal kingdom before the specific features are for the 

 most part fully sketched out, if not completely developed. 

 Can there be any doubt that the human embryo belongs 

 to the genus Homo, even before it has cut a tooth 1 Is 

 not a kitten or a puppy distinguishable as a cat or a dog 

 before the claws and teeth tell their genus \ Is not this 

 true also of the Lamb, the Kid, the Colt, the Rabbits, and 

 the Mice, of most Birds, most Reptiles, most Fishes, most 

 Insects, Molmsks and Radiates 1 ? And why should this 

 be ? Simply because the proportions of parts, which con- 

 stitute specific characters, are recognizable before their 

 ultimate structural development, which characterizes 

 genera, is completed. 



1 PR. M. v. NEU-WIED quotes as a is still a pale, almost colourless 



remarkable fact, that the Chelonura embryo, wrapped up in its foetal en- 



serpentina bites as soon as it is velopes, with a yolk larger than itself 



hatched. I have seen it snapping in hanging from its sternum, three 



the same fierce manner as it does months before it is hatched, 

 when full-grown, at a time when it 



