70 PALEONTOLOGY OF CALIFORNIA. 



the same pattern, differing only in size, and consequently in com- 

 plexity of their minuter details. They are bifurcate, each branch 

 being divided into two or three spurs ; above these branches are 

 two spurs on each side, all being finely dentate. Saddle deeply 

 divided for more than half its length, each branch bifurcate. This 

 septum approaches that of Ammonites .Batesti, but differs in many 

 of its details ; the smaller lobe being towards the dorsal margin, 

 and apparently occupying the place of the superior lateral, is a 

 well-marked character. The ornaments of the surface are also 

 very peculiar. 



The reference of this shell to the genus Ammonites may pro- 

 bably prove to be incorrect. Two or three specimens were col- 

 lected, the best of which is figured. No whorls having been 

 found in contact, it may prove to be a Helicoceras, or even Hamites. 

 It is of particular interest from the fact that it is one of the oldest 

 fossils found in the southern part of the State, being considerably 

 below the newer Cretaceous fossils of San Diego. 



Locality : From a shaft sunk in search of coal on the west side of Point Loma, 

 opposite La Playa, San Diego, and presented by Mr. E. W. Morse to the Geolo- 

 gical Survey. 



HAMITES, Parkinson. 

 H. Vancouverensis, n. s. 



PI. 13, Fig. 18. 



Shell large, section elliptical, longest diameter from dorsal to 

 ventral side. Inner width of the curve less than the diameter of 

 the smaller arm.- Surface marked by numerous sharp ribs crossing 

 the shell, inclined obliquely forwards; well marked, but diminished 

 in size on the ventral side; largest laterally; each rib carrying a 

 small flattened tubercle on the latero-dorsal angle ; some ribs in 

 the curve, on the ventral side, exhibit a tendency to tubercula- 

 tion, but, the shell being broken off at that point, their presence 



