ELA.LOGY. 



arietian type in the form and sutures of An ind from this the typical 



- of the family, Coroniceras, was evolved. The keel, donble-chanm 

 abdomen, Btraight geniculated pilse, and less complicated sutures of I »« » 1 1 * genera, 



ular to those of Vermiceraa in the Plical 

 This normal type was rapidly departed from in the next branch, in which 

 the highly aberrant compressed I ( ippeared. This aberrant ten* 



dency was still more decidedly brought out in the <■ rapid production of 



similar, but more compressed and involute, forms in Oxynoticeras. In this, also, 

 the highest specialization was reached by the introduction "i a new structure, 

 the hollow keel, as a nealogic and ephebolic characteristic. 



The smooth variety <>f Pail, pbmorbe, and its immediate congener, Ptii. catiphyl- 



the most primitive forms which occurred in i ; I nd we 



can treat the whole of the tw< - a connected group arising in Central 



Europe from the smooth variety of phmorbe, though, as a matter of fact, this is 



bly artificial. The actual process of the evolution of the second branch, and 



1 oceras, as will be explai 1 in Chapter III . took place in the 



Northeastern Alps, and the forms found in Central Europe were 

 nts. When arranged naturally the genera appear as in the Summary 

 in asseml stinct and more or let 



\\ ■ ■ ■- I each separate genetic series as a genus, 



- nv to 'l<> tlii-. or else use n cumbersome trinomial or quadrinomial d< 



live nomenclature. Even with the aid of binomials, we have m>t been able t<> 

 speak of any series under one name ac Had this rule been 



adopted, i. <•. t" treat each seri ogle Bpecies, the <»]>int<ni- of paleoi 



ire 1 1 ■ » r now in it- favor, and probably no one would have followed us in 



e. however much disp >1 theoretically to praise >>^v conservatism. 



.n hi< most recent work has proposed none- i « .r the different g 

 etidoB all ending in They are highly appropriate euphon 



but tor the most pari are open viol priority in not 



ami i iti»- in arrangement, though supported bj ind a 



the highest importance to all stu- 

 this branch of 



■1 to show, in the Introduction and in other parts of this essay, 

 that the metamorphoses of a normal individual in all »a trust w 



index <>: the morplio group, and that a group of species tended to 



'e of I'm in these metamorphoses. 7 



also be further defined 

 indep which must always be represented '•■ 



line when ted graphically in s 



i table. In such exam] 



■ 

 •it in the nealo} of their 



