44 ANNUAL REPORT OF 



variants, may be supposed to throw off in turn smaller particles, 

 corresponding to species, which radiate in the same manner. 

 Some will be precipitated at tangential extremes, halting finally 

 when resistance overcomes their momentum; others will strike 

 downwards in a retrograde path, and shortly disappear — these 

 being the so-called degenerate species. And still others will be 

 given an impetus in an upward direction, their movement contin- 

 uing until they too> are overcome by resistance. These last are 

 the progressive species, and it is evident that only amongst this 

 class can any persist and keep pace with fresh competitors that 

 are constantly entering the field at higher levels. Certain ones 

 that persist longer than others thus come toi stand out in the 

 changing- complex as archaic types, their antique characters con- 

 trasting strangely with the remodeled order O'f things. 



The parallelism we have imagined is, not exact, but may serve 

 as a graphic portrayal of the manner of succession and decadence 

 of species and higher groups. One meets with a closer analogy 

 in studying the history of languages, or of individual words in 

 a single or in various languages. Every one knows that certain 

 primitive roots, especially designations of essential objects and 

 relations, have survived from early Aryan speech down to mod- 

 ern times; and innumerable cognate expressions exist side by side 

 in European tongues derived from the Latin and Greek. Roots 

 and stems, that is to say, the ground types, persist practically 

 unchanged throughout all the vicissitudes and changing condi- 

 tions of human progress. Variations, too, once firmly estab- 

 lished, and favored by environment, are apt to persist indefinitely. 

 Not only do words, idioms and figures of speech all illustrate the 

 principle of evolution, but standards of pronunciation furnish 



earliest known member of this order (Cheirolepis) appears as an insignificant 

 item in the Lower Devonian fauna, where crossopterygian and dipnoan fishes 

 are dominant. When the latter begin to decline in the Lower Carboniferous, 

 the suborder to which Cheirolepis belongs (Chondrostei) suddenly appears in 

 overwhelming variety. By the period of the Upper Permian another funda- 

 mental advance has taken place — the Protospondyli have arisen; but only a 

 solitary genus is observed among the hosts of the dominant race. In the Trias 

 the new type becomes supreme, and at the same time the next higher suborder, 

 that of the Isospondyli, begins to appear. This lingers on in the midst of the 

 dominant Protospondyli during the Jurassic period, and then in the Cretaceous 

 this and still higher suborders suddenly replace the earlier types and inaugu- 

 rate a race which has subsequently changed only to an insignificant extent." 



