118 



University of California Publications. [Geology 



(a) Teeth flat, little curved, with the serrations mostly 20 to 40 on each 

 side ; height of tooth less than two inches ; no trace of basal 

 denticle 



(6) Teeth relatively narrow, with moderate serrations. (Species living) 



carcharias 



(bb) Teeth broad, with strong serrations; each tooth with a suggestion 



of a median ridge riversi 



(aa) Teeth more strongly recurved, without median ridge; serrae more 

 than 40 on each side 



(o) Base of tooth on each side, with a serrated protuberance or den- 

 ticle ; tip of tooth entire ; serrae 50 to 60 on each side rectus 



(cc) Base of tooth without denticle; tip of tooth serrate, like the side 



(<l) Teeth rather narrow, the serrae rather strong, about fifty on each 



side arnoldi 



(dd) Teeth broader, larger, three to four inches high; serrse fine, eighty 



to one hundred on each side branneri 



For the present these types of teeth may be regarded as be- 

 longing- to different species of Carcharodon. 



Family DALATIID.F. 

 Genus Dalatias. 

 {Seym ii us Cuvier. ) 

 21. Dalatias occidentalis (Agassiz). 



(Scymnus occidentalis Agassiz, Am. Jour. Sei. Arts, 1855, 

 p. 72; Oeoya Creek.) 

 This species is said to be distinguished by "the strong bend 

 backwards of the main point of the tooth, and the distinct and 

 rather marked serration of the edges of the crown." The lower 

 teeth in Dalatias are erect, triangular, and serrated. The upper 

 teeth are smaller and more simple. 



To this species I refer with some doubt one small tooth from 

 the collection of Dr. J. J. Eivers, in the Pliocene rocks of Temes- 

 eal Canon, in the Santa Monica Range. I am not quite sure that 

 this is Agassiz 's species, but the identification is probable. This 

 tooth is sharper at the point than is shown in Agassiz 's figure; 

 the point is strongly hooked outward, and each side of the base 

 of the tooth has about seven strong denticles ; the cusp is nearly 

 entire, the tip quite so. The form of the tooth suggests Galco- 

 cerdo, but the tooth is much flatter than in the latter. Four 

 similar teeth are in the collection of Mr. F. M. Anderson from 

 four miles east of Oil City. 



