CARCHARODON 9 



Family LAMNID^ 

 1. Carcharodon arnoldi Jordan. 



No teeth of sharks have been found in the diatom deposits. In the 

 breccia which overlies part of these beds, shark's teeth occur occasionally 

 among the broken bones of whales. 



We obtained two such teeth corresponding to the form called CAR- 

 CHARODON RIVERSI Jordan, which we take to be a back tooth of the 

 common CARCHARODON ARNOLDI. 



Family CLUPEID^. 



2. Xyne grex Jordan and Gilbert. 



(Plates I, II, III) 



In the original description of this species (Jordan and Gilbert, Fossil 

 Fishes S. Cal., p. 25) it is stated that numbers XXIV and XXVIII, 

 Stanford Collections, came from Bairdstown. This is an error : all came 

 from the same stratum as the type slab (CVIII) from Lompoc. 



Outside the mass of this species, which covers four square miles of 

 deposit all at the same geological level, this fish is scantily distributed 

 through the rocks higher up. 



The most remarkable feature of the diatom beds is the evidence of a 

 tremendous catastrophe which overwhelmed millions of individuals of 

 this herring, at a single moment, apparently in the spawning season. 



It is evident that these fishes were gathered together in the sheltered 

 bay in which these deposits occur. At a horizon 950 feet from the base 

 of the deposit is the layer of this species. The individuals are of about the 

 same size (6 to 8 inches) lying flat, not distorted nor much piled. All 

 are in the same horizon and this wherever opened is covered with these 

 fishes. No other species is mixed with them, and there are but few 

 remains of the species in the rocks higher up. Nearly all these specimens 

 are dark brown or black, showing them to have been carbonized. In the 

 rocks above, this and other species are mainly prints merely, the marks 

 of their bones being replaced by diatoms. 



Of this species numerous slabs were obtained, through the energetic 

 help of Messrs. Krieger, Porteous, and Starr, and Mr. John Sells, fore- 

 man. These were taken from a tunnel near the north side of the deposit. 

 The largest slab is about eight feet by four, containing hundreds of 

 individuals. 



The genus XYNE is characterized by a symmetrical herring-like 

 form, the belly, however, compressed and armed with sharp lanceolate 

 scutes, the dorsal nearly median and opposite the ventrals, the bones of 



