CRETACEOUS FOSSILS. 69 



number and carry large tubercles, and the difference of the sep- 

 tum is sufficiently marked to distinguish them. 



Localities : Chico Creek, collected by Dr. Trask ; Pence's and Kelly's Eanchos, 

 twelve miles north of Oroville, Butte County ; Siskiyou Mountains, Siskiyou 

 County ; and I have found a single specimen on the Rancho de Sari Luis Gonzaga, 

 Pacheco's Pass, Merced County (Div. A.). 



A. COMPLEXUS ? 



(A. eomplexus, H. and M. Trans. Amer. Acad, of Arts and Sciences, 2d series, 

 vol. 5, p. 394, PI. 4, Fig. 1.) 



A specimen in the collection of the California Academy of Natural Sciences, 

 from the debris of the Cretaceous at Folsom, probably belongs to this species. 

 The external shape agrees with the specimen figured in the plate quoted above, 

 as well as does the septum, as far as I have been able to trace it. It differs, how- 

 ever, in having distant, well-marked ribs, which arch forwards and cross the dor- 

 sum. There are fourteen of these on half a whorl, of a specimen originally about 

 five inches in diameter. The ribs are most prominent on the latero-dorsal portion 

 of the whorl, heing nearly obsolete on the back itself. I can only refer it doubt- 

 fully to the above species, though I trust that 1 shall hereafter be able to settle 

 the point ; more particularly on account of the valuable link in the chain of evi- 

 dence of the parallelism of the California Cretaceous with known beds on the 

 eastern side of the continent. A variety of this species has been described by Mr. 

 Meek from Vancouver Island, under the name of A. eomplexus, var. Suciaensis. 



? A. Cooperii, n. S. 



PI. 14, Fig. 23, and 23 a. 



I propose this name for a Cephalopod from near San Diego, of 

 which I have onhy seen fragments, very much compressed. The 

 surface is ornamented by two rows of nodes (on the side ?) with 

 ribs extending across, some passing through one, some through 

 two of the nodes ; while others originate in one and end in an- 

 other. By the peculiar arrangement of the ribs, there are about 

 a third more on the middle of the fragment than on the margins. 



Septum : The fragment exhibits two lobes and one and a half 

 saddles. The small lobe on the diagram is placed on the upper 

 (dorsal ?) side of the upper row of tubercles. Both lobes are of 



