THE PALEONTOLOGIC RECORD 297 
no necessary relation to the onto-stages, even if they coincide with them. 
We have thus a second group of stages, which we may designate form 
stages, or morphic stages, and there will be required distinct designa- 
tions in each case. The best method of naming these stages is to refer 
them to the adult ancestral type which they represent. 
Thus, in all species of the gastropod shell F'wsus, the earliest morphic 
stages are a close recapitulation of the adult of Fusus porrectus of the 
Kocenic. These stages may therefore be called the F. porrectus stage. 
It may be continued for a considerable period of the early life history, 
covering several onto-stages, or it may be condensed into a short por- 
tion of one stage or substage, in accelerated individuals. 
It is of considerable importance that onto-stages and morphic stages 
should be discriminated, so I will introduce another illustration. 
In the Miocenic of the Atlantic coast we have the gastropod genus 
Fulgur well represented. Fulgur fusiformis is normally characterized, 
in the adult, by the possession of a pronounced flat shoulder, which is 
separated from the body of the shell by an angulation carrying rounded 
tubercles. Some of the more specialized individuals lose the angula- 
tion and tubercles in the last whorl and become rounded. Thus, while 
normally the species is tuberculated in the ephebic onto-stages, special- 
ized individuals acquire a new morphic stage through the loss of orna- 
mentation. ‘This morphic stage is prophetic of the normal adult of 
Fulgur maximum, and hence may be called the F. maximum stage. 
F. maximum itself has in its nepionic onto-stage the characters of 
adult F’. fusiformis ; hence it may be designated the F. fusiformis stage. 
Some individuals acquire a new stage, namely, a spinous stage, char- 
acteristic of the adult of F. carica. In the type designated as F. 
tritonis, the nepionic stage is characterized by a fusiformis morphic 
stage, the neanic largely by the maximum stage, though some of the 
later neanic stages may actually acquire the carica stage. In less 
specialized individuals the maximum stage may continue into the early 
ephebic in more specialized ones it ceases early in the neanic, the carica 
stage taking its place. Finally, Fulgur carica is characterized by the 
elimination of the maximum morphic stage, so that the neanic as well 
as the ephebic onto-stages are characterized by the spines of the carica 
stage, which may even begin in the late nepionic. 
In the foregoing, the different morphic stages are shown to be 
telescoped with the onto-stages, appearing either earlier and earlier in 
the ontogeny of successive individuals, through the operation of the 
law of acceleration or tachygenesis; or later and later, through the 
operation of the complementary law of retardation or bradygenesis. 
These laws are, of course, only applicable to an orthogenetic series, but 
in such a series they are competent to produce, by interaction, all 
conceivable combinations of characters. 
