Apr. 1899. Paleontology of Upper Cretaceous Series — Logan. 209 



petuate racial characteristics. That these suppositions do not accord 

 with the facts is a further confirmation of one of the laws of evolu- 

 tion. It is confirmatory of the law that as characters of development 

 first show themselves in the adult, so also do degenerative characters. 

 In other words degeneration takes place in the inverse order of 

 development. The order of development of the Cephalopods, as 

 shown by Hyatt, has been in regard to form: 1. the straight shell ; 

 2. the arcuate shell ; 3. the loosely coiled shell ; 4. the closely coiled 

 shell. Along with this development of the form of the shell has 

 gone an increased development in the complexity of the sutures. 

 Scaphites is considered degenerative in form because of the tendency 

 exhibited in the adult to return to an early form by a partial uncoil- 

 ing of the shell. If this be true degeneration, it has not as yet affected 

 the sutures. 



In fact the phylogeny of the genus reveals progression rather 

 than retrogression. As an illustration compare the suture of Scaphites 

 warreni . Meek, Fig. 1, PI. XXII with the suture line of Scaphites no- 

 dosus Meek, Fig. 2, PI. XXII. 



The first is a Benton species while the second is a Pierre species. 

 The first, therefore, is the primitive form as regards time and suture. 

 Furthermore the ontogeny of 6". nodosus reveals a stage which cor- 

 responds with reference to the suture very closely to the adult suture 

 of S. warreni. It seems very probable, then, that the latter is in the 

 line of the direct evolution of the former and represents an earlier stage. 

 The changes in form as revealed by the two species do not point to 

 any marked degree of retrogression. The principal changes have 

 been an increase in the size of the individual; an increase in the 

 complexity of the suture lines; and the development of two rows of 

 nodes, one on the umbilical shoulder and a second on the ventral 

 border. In 6*. warreni the ornamentation consists of strong ridges 

 with a tendency toward nodosity in some individuals. In the young 

 of S. nodosus the ridges are well marked while the nodes are entirely 

 absent on the umbilical shoulder and not prominent on the ventral 

 border. 



In the excellent work of Branco although Scaphites is mentioned 

 in the list of genera its ontogeny is not exhibited. The omission was 

 no doubt due to a lack of workable material. And, indeed, this was 

 at first a serious obstacle to the success of the present writer. Owing 

 to the highly crystalline character of the calcium carbonate which 

 preserved the form of the shells many specimens were broken up 

 without results. Later, from some young forms furnished by Prof. 

 Weller, of the University of Chicago, the results recorded below 



