78 KANSAS UNIVERSITY SCIENCE BULLETIN. 



Cephalo-dorsal processes occur on the palatines of speci- 

 mens Nos. 812 and 379 of Enchodus amicrodus Stewart, plate 

 X, figures 2 and 3 ; also in specimens Nos. 831 and 827 of En- 

 chodus dolichus, plate XIV, figure 1, and plate XV, figure 11, 

 pal, respectively. These processes do not occur on the other 

 specimens. This is somewhat surprising, since Doctor Loomis 

 records having observed, on almost every palatine examined, 

 "a spur of this fold." (Loomis, 1900, p. 275.) The spur re- 

 ferred to certainly can be no other than the cephalo-dorsal 

 process described, since no other similar process is to be ob- 

 served on any of the other numerous palatines in the American 

 forms represented in the museum of the University of Kansas. 



A detailed study of the cephalic end of the palatine sug- 

 gests a possible explanation of this spur. Note that in the 

 longitudinal median sections, shown in figures 15 and 17 of 

 plate VII, the bases of the fangs (a, b, c, d, etc., of both 

 figures) are, at their dorsal ends, somewhat concave in front; 

 but that this is much more marked in figure 17 than in figure 

 15. Microscopic examination of the cephalic surface of the 

 last functioning base of figure 17 indicates a structure uni- 

 formly porous from the surface inward. This would indicate 

 that it does not represent a permanent bone surface, but sug- 

 gests that considerable of the cephalic portion of each base is 

 absorbed before the deposition of the layer of tissue which 

 will thicken to form the base of each succeeding fang. If this 

 hypothesis is true, the cephalo-dorsal process would not al- 

 ways be equally prominent, nor would the prominence indicate 

 the formation of a new base, but it would be largest at the 

 inception of each new base and most inconspicuous at its 

 completion. Why this absorption should be more marked in 

 some species than in others can not be determined with present 

 data. 



The succession of teeth is described by Cope in the following 

 words : 



The first teeth appear on the alveolar border at a considerable dis- 

 tance apart. The second teeth appear immediately in front of these, 

 and by their presence create the irritation which results in the absorp- 

 tion of the root and shedding of the crown of the first. The teeth of 

 the third series appear in advance of the second, occupying the space 

 between them and the empty space previously occupied by No. 1. They 

 may coexist for some time with teeth No. 2, as the specimen indicates, 

 but the result is, as before, the shedding of the adjacent older teeth. 

 In case of the anterior long fang of the dentary, the movement is re- 



