64 



BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



specimen of St. John and Worthen. Twelve teeth are now visible in the 

 foremost row on the right-hand side of the Cambridge specimen; 13 

 are to be seen in the second row ; and of the third row, which has been 



fractured across, and hence ap- 

 pears only in section, only 6 

 remain. The largest tooth in 

 the foremost of the antero- 

 lateral series has a length of 

 2.1 cm.; the largest in the 

 second row, 3 cm. Other meas- 

 urements that may be con- 

 veniently recorded here are as 

 follows : A straight line drawn 

 from the apex of the posterior 

 to the anterior symphysial 

 tooth in the Kansas specimen 

 measures 20 cm. ; and a line 

 joining the terminal apices of 

 the Kebraska specimen lias a 

 length of 16.5 cm. The maxi- 

 mum width of the symphysial 

 series is G cm. in the former 

 example, and 6.2 cm. in the 

 latter. The conformation of 

 the individual teeth being suffi- 

 ciently evident from the fig- 

 ures and cross-sections, further description here is superfluous. The 

 cross-section shown in text-figure 2 is talcen through the fourth tooth 

 from the front in the Kansan specimen, except that the vertical thickness 

 in the median line is estimated from the most anterior tooth, which is 

 the only one displaying this dimension. In the Nebraska specimen the 

 vasodentine of the roots is largely decomposed. 



Fig. 2. 



Campodus variabilis (N. & W.). Missourian ; 

 Osage County, Kansas. Generalized cross- 

 section of a symphysial tooth. X f . 



Carapyloprion. 



(Plate 4.) 



This genus was established for the reception of certain forms occupy- 

 ing an intermediate position between Edestus s. s. and Helicoprion. 

 The latter genus is known at present only by the type species, M. besson- 

 owi Karpinsky, from the Permo-Carboniferous of Russia. Edestus in its 



