THE DEVELOPMENT OF SCAPHITES 651 



the writer has come to the conclusion that Baculites and Lytoceras, and 

 these two species of Scaphites, had a common ancestor, or Baculites 

 and Scaphites may have sprung from the Lytoceratidce. Indeed, 

 some are of the opinion that Baculites came from the Lytoceratidce, 

 and is a very degenerate descendant from this more normal and 

 progressive family. The likeness of the young stages of S. condoni 

 and inermis to the young of Baculites and Lytoceras is more in the 

 general aspect of the shell rather than in any specific characters. 



The interior forms of Scaphites soon change to forms with narrow, 

 deep umbilici, and come to possess prominent ribs, while the two 

 Pacific province forms do not develop in this manner at all, but 

 remain thin and possessing wide umbilici. (See Numbers 8 and 9, 

 Fig. 2.) 



ACCELERATION AND RETARDATION 



Logan, in the above-cited article, said that the Scaphites from the 

 Interior Sea, Scaphites nodosus group, were progressive ammonites. 

 The writer is forced to take issue with Logan on this point. He 

 concludes that they are not progressive, but degenerate forms, and, 

 moreover, forms exhibiting unequal acceleration of certain characters, 

 and hence retarded in the sense that Cope 1 meant. J. P. Smith 2 gives 

 a summary of the work of Hyatt, Cope, and others on the underlying 

 philosophical principles of paleontogeny, and the two laws, the former 

 of which was formulated by Hyatt, and the second by Cope, are 

 explained, so that they will not be stated again in this paper. 



In the first place, both of these groups of Scaphites are degenerate, 

 and they are considered so on these grounds: (1) in the possession 

 of an abnormal body chamber, they show degeneration or senility; 

 (2) in the dicranidian lobes ; (3) in the reduced number of lobes and 

 saddles; (4) in the fact that they have, so far as we know, left no 

 trace of a descendant. 



Pompeckj 3 concludes that the possession of the abnormal body 

 chamber marks that particular ammonite as senile, and when the 



1 E. D. Cope, Origin 0} the Fittest. 



2 J. P. Smith, "Comparative Study of Paleontogeny and Phylogeny," Journal of 

 Geology, Vol. V (1897), No. 5, p. 508. 



3 J. F. Pompeckj, "Die Ammonoideen mit anormaler Wohnkammer," Jahres- 

 hefte des Vereins }iir V aterlandische Naturkunde, in Wiirtenberg, 50! Jahrgang (1894), 

 pp. 220-90. 



