Geol.— Vol. II.] ANDERSON— CRETACEOUS DEPOSITS. 7 1 



Part II. 



Description of Species. 



In the following descriptions of fossil species, it has been 

 the endeavor, whenever possible, to recognize from previ- 

 ously published figures and descriptions the forms that have 

 been found by others and listed as authentic species. 

 There are among the collections of the University of Cali- 

 fornia many type-specimens from which Gabb's original 

 descriptions were made, and considerable other material 

 which was labeled by Mr. Gabb and turned over by the 

 State Survey to the State University. Such material has 

 proved to be of great service in the identification of species 

 described in the publications of the State Geological Sur- 

 vey. Much kindly interest has been shown, and great 

 assistance given in the preparation of this paper, by those 

 chiefly interested in extending our knowledge of West 

 Coast geology, and especially of Pacific Coast Cretaceous 

 deposits. 



It is not improbable that when the Cretaceous fauna of 

 California becomes better known many of the species that 

 have been described as new will prove to be either identical 

 with, or very closely allied to, Atlantic or to other Pacific 

 forms. It is with this feeling that man}^ of the names are 

 proposed in the present descriptions; but an identification 

 of this kind will not be retarded by the attachment of mere 

 names, while the published descriptions of these forms will, 

 it is hoped, stimulate closer comparison. 



It is evident to any one familiar with the different types 

 of the genera Lytoceras and Desmoceras that too much lax- 

 ness has been allowed in the determination of species. 

 Forms that have barely more than a general resemblance 

 have been included under a common name. Note, for 

 example, Desmoce?'as jtigalis, Desmoceras hoj'nianni, Lytoc- 

 eras batesi, and many others. 



