373 



tlnguisli tliese forms. When we compare the septa, however, they are 

 at ouce seen, to present marked differences, such as are clearly incom- 

 patible with specific identity, if d'Orbigny's tigures are accurately drawn. 

 It is also closely allied to A. 3£oreUamis, d'Orbigny, but differs in the 

 structure of its septa. 



Locality and position. — Cretaceous beds at Komooks, Vancouver's 

 Island ; also in the lower division of the Califorcia Cretaceous at Cotton- 

 wood Greek, Shasta County, of that State. 



Geniis NAUTILUS, Linnaeus. 

 Nautilus Campbelli, Meek. 



Plate 6, figs. 2 and 2 a. 

 Nautilus CamphcUi, Meek (1861), Proceed. Acad. Nat. Sci. Philad., 318. 



Shell large, subglobose, or somewhat oval, moderately convex ; pe- 

 riphery and sides rounded or slightly compressed ; volutions increasing 

 rather gradually in size, deeply embracing, and rounding into the um- 

 bilicus on each side; umbilicus very small, but not quite closed; septa 

 separated by spaces less than one-third the transverse diameter of the 

 whorls at the point of measurement, arching slightly backward on the 

 sides and periphery ; aperture nearly circular, but deeply sinuous on the 

 ventral side for the receptions of the inner whorls. Siphuncle and sur- 

 face-markings unknown. * 



Length, or greatest diameter, 4.S3 inches; breadth, or transverse 

 diameter, 3.07 inches. 



This fine Nautilus is much like N. Clementinus, d'Orbigny, as figured 

 in his Paleont. Frangais, Terr. Cret., i, pi. 13 bis. It differs, however, 

 in having a more rounded aperture and a more broadly-rounded j)e- 

 riphery, the entire shell being less compressed. 



It is perhaps more nearly allied to some varieties of the Indian form 

 referred by Dr. Stoliczka to iV". Bouchardianus, d'Orbigny (= N. Iwvigaius 

 and N. sphcericus, Forbes), some of which seem to be nearly as much 

 compressed. None of these forms, however, show near so rounded an 

 aperture or section of the volutions. Yet it is extremely difiBcult 

 to distinguish these smooth Nautili of this type with such specimens as 

 we usually get for study, and it is therefore possible that more exten- 

 sive collections may show it to be necessary to unite the Vancouver shell 

 with one of these foreign species. 



It may be at once distinguished from Nautilus Dekayi (which has been 

 identified by Dr. Shumard from Vancouver's Island) by its much more 

 compressed form, narrowed aperture, and slightly open umbilicus, that 

 of N. JDelcayi being entirely closed at all ages by a solid shelly colu- 

 mella. Its whorls are also more compressed on the sides, and more 

 concave in the region of the umbilicus, thus giving a very ditiereut form 

 to its aperture and the section of its volutions. 



The specific name was given in honor of Mr. Archibald Campbell, the 

 commissioner in charge of the Northwestern Boundary Survey. 



I have given on the same plate (Fig. 3) for comparison, an outline 

 showing a transverse section of one of the whorls of Nautilus Dekayi^ 

 taken from Dr. Morton's original specimen, in the collection of the 

 Academy of Natural Sciences at Philadelphia. 



Locality and position. — Komooks, Vancouver's Island ; Cretaceous. 



