I.\\\ OF V I EU R \ I I"N II 



compressed, involate forms 1 : v I . the suppression, so far as we 



know, always occurred in normal forms at some n ad the pr» 



of i channel i-< constant even in the young. If th< 1 the 



nen, thus ol>li- scuring the channel, during the life of the 



game individual, it occurred as a degradataonal character in tli 

 I 1 1 it ni in Bpecies <li.l not occur in Schlotheiraia, but if 



there bad I n any such nostologic forms, they would have inherited tlii- ten- 

 dency the channel during the neal rhe law i 



velopment was quite as effective in its action up 

 as upon pi characters, as will l>e seen when we tiv.it of this cl 



chai ber on. 



l; ■ the examples given above of the inheritance of characters in I 

 am] smaller series, we add the following in order t" make our meaning still i 

 The form, Bhape, and characteristics <>r the secondary radical, PsU. p 

 prominently shown in the young of Am P >' II Fig. 10-15, and in the 



Embryology of Cephalo] 9, 1<». until a late j >«-ri« .< I of the 



; i of the shell, but are eable in the young of the descendent 



lion, in which indeed they are perceptible only in the transition 

 form between thi< Bpecies and Most of the specimens have ; 



like that figured on Plate III. Fig. _. and are stouter than the flat discoid. 



These and the young of other Bpec I liceras inherit the Btouter 



qnadragonal whorl and peculiar ribs and tubercles, the keel, and the channels, 



of their growth than those in which they fir>t appeared in ai b- 



tral shells, as may \«- Been by comparing .1 tUtfum with the young of 



I Fig. 19, and F B 10. 



(>nc «.f the most convincing examples of the law of acceleration which we 



studied can be illustrated by using Wright's 1 k. •• Lias Ammonites." ' He 



form of the young on Plate XXXI V., and in Fig. I— 6 the 

 adult m. A a 



ii shown on Plate XXXV. Fig 1—6, in which the young arc similar to 

 prolonged period of their growth. Wright's ./.' // 



XXXIll . is ah men of the same bj ies with a prolonged latss- 



•'. / // red by Wright 



XI. 111. is also higblj accelerated, and most of the specimens have 

 shell- with no • ii ancestry, reproducing only the char* 



lult whorls / B figured by 



II in a in its mode of development, 



•m!. 1 me. • to the adult of And From the si 



if the n.Tpionic period "f growth it passes abruptly to a stage in which the 

 sh.il i the adult form I be whorh 



the adull h 



I to their - 

 with the adult ol 



