■ : 1 . N « LATl - . i.l;<"\\ ill AND DECLINE. 19 



Th- i rule inherited or homogenous within the 



i which they originated, but arc n.>t transmitted from one 



;it through the medium of the ne if what we have 



called the .' and tbev are not, bo far a- we know, ever concen- 



in the earliest larval <>r nsapionic Btages; thej occur too late in the 



• 



- fy in the. nealogic and ephel : i characters as follows: 



irply defined ridge-like pilaa and tubercles, the channels with their lateral 



-.anil keels, and especially the hollow keel, the highly developed rostrum 



of the higher Bubord< illy Ammonitins, the lateral lappets of the aper- 



nnl the branching marginal lobes and Baddies of the Butures of suborders 



iatitinsB. Speaking in a general way. we should include in these 



those progressive characters which appear late in the life of the 



shell among the higher Buborders, and at the acme of their development in 



tame, which arc not found in the Btock of discoidal radical forma When the 



shell ie the ribs or pike, as we prefer to call them, the n< 



said In a general way to have been entered upon. It \i>< been 



found that thes of growth indicated genetic relationship with radical 



fornix, which were not infrequently merely different genera or species within 



the limit- of the same family, and • irred on the Bame or only Blightly 



nt horizons. The nealo the higher Ammonoids, Ammoni- 



tinaB and I. taa, have not the constancy and general importance of the 



imt are transient in the history of the types, appearing and 



_r in the same limited series <>i" forms. They consist of the less im 



nl modifications which first appeared in the adolescent or adult Btages at 



period in the history of a type, and were then inherited in the nea 



: the Bame Beries, according to the 



ii of the law of acceleration. The nealogic category cannot he as 



i from the ch from th" f the 



i .nice iii adults indicated the establishment of a new 



nee they are invariably differences bo far as their 



rs in the Bami ncerned. However much 



they i: ill other series, they 



•in- adult ' ancestral Bpe< 



Thus ti i rule ephebolic, and not 



: n nmong the Cephalopoda, ami usually become nealogic through 



I have frequent occasion farther on to call in the evidence 



of tie ml to -how. a- ill tie' End) ratiTe. tint. a< a rule. 



• tell in tii i ih. as indeed must have been the 



i an'l the microsiphon. 



.V •! of the which ended with tie full 



-. tie- iii-' lecline, or th.' 



nee. nnd became more and n 

 I .ml that, 



