Geol— Vol. II,] A.WDERSOM— CRETACEOUS DEPOSITS. 1 23 



number being about seventy-two, most of which belong 

 to the secondary class, not passing above the middle of 

 the sides. 



Occurrence. — This species was found abundant at both 

 the Forty-nine Mine and at Smith's ranch, two miles to 

 the northwest, near Phoenix, Oregon. It belongs to a 

 horizon equivalent to the Lower Chico of the Sacramento 

 Valley. 



The types are in the collections of the California 

 Academy of Sciences. 



70. Schlcenbachia propinqua Stol. 



Plate II, Figs. 34-38. 



Ammonites propinqmis Stol., Pal. Ind., Vol. i, p. 53, PI. XXXI. 



The species of Schlcenbachia which is believed to be 

 identical with the Indian form agrees so well in its meas- 

 urements and surface markings with Stoliczka's figures 

 and description, that were it found in the same region there 

 would be no hesitation as to its specific determination. In 

 sutural features, however, there seems to be a slight dif- 

 ference, though not sufficient to warrant a specific dis- 

 tinction. The suture represented in the figure is from a 

 younger whorl than that of Stoliczka's figure, having a 

 diameter of only 3.5 cm. 



The shell is discoidal and flattened at a diameter of 2 or 3 cm., but becomes 

 thicker with increasing growth. At the diameter of 4 cm. the section of the 

 whorl is elliptical. The ribs of a single whorl number from forty to forty- 

 four, showing a tendency to bifurcate a little below the dorsal, or umbilical 

 margin. The keel, at first simple, becomes at a diameter of about 2 cm. 

 broken up in slight undulations. 



This species is distinguished from 5". oregonensis not only by the smaller 

 number of ribs, but by a number of important and minor differences. 

 S. oreg07iensis lacks the prominent umbilical tubercules of the former; its 

 sides are also more flattened, the keel less conspicuous in older and in 

 young shells, and the abdominal area is more angular. Moreover, in 

 S. oregoncfisis this abdominal area is distinctly crossed by the ribs at the 

 diameter of a little over 3 cm., which does not appear to be the case either 

 in Stoliczka's figures or in the specimens from Southern Oregon. The 

 sutures show still more important differences, which only a comparison of 

 the types or the figures will make apparent. 



