TRIASSIC FOSSILS. 27 



of the diameter of the shell; margin rounded; whorls increasing 

 very gradually in size in the young shell, afterwards more 

 rapidly; aperture subcordate ; surface plain; septum composed 

 of a dorsal and two lateral lobes. From the condition of the 

 specimens, I have not been able to obtain the details ; but the 

 lobes appear to be quite complex, with a tendency to throw out 

 long slender spurs. 



Figure, natural size; fig. a, section of the body whorl. 



Locality : With the preceding. Collected by Mr. Homfray. 



Named in honor of Mr. E. Billings, of the Geological Survey of Canada. 



A. Ramsaueri? Quenst. 



PI. 3, Fig. 21, 21 a. 



(A. Ramsaueri, Q. Hauer ; Die Cephalopodon des Salzkammergutes, p. 22, pi. 8, 



figs. 1, 6.) 



Two or three imperfect specimens of this Ammonite were found by Messrs. 

 Brewer and King at Giflbrd's Banch, Plumas County, the most perfect of which 

 is figured. They agree in all external characters with figures 5 and G above 

 quoted; and, in the absence of proof to the contrary, I have referred them to 

 Quenstedt's species. The peculiar, irregularly placed, nodose ribs, the minute 

 umbilicus, and the evidently subglobose form of the shell before distortion, forbid 

 a separation ; unless larger specimens should want the angle which forms on the 

 dorsum of adults of the European form ; or some difference should be detected in 

 the septum. 



Two or three fragments, showing merely a portion of the side of one volution, 

 collected by Mr. Homfray, associated with A. Homfrayi and A. Billing sianus, should 

 probably be referred to this species. 



The identification of this shell — A. Ausseanus — and one or two other species, 

 with known European forms, together with the close resemblance of others to 

 their European congeners, as well as the great similarity of type between nearly 

 all of the forms in the American and European deposits, point at once to a nearly, 

 if not perfectly, complete synchronism between the Trias of the Sierra Nevada 

 and that of the Alps. 



