372 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



also in the wider umbilicus. There are, however, in the 

 American Trias species with as narrow or even narrower 

 umbilicus than M. boreale, but in them all the auxiliary 

 series is as in M. gracilitatis. 



Horizon and locality. Meekoceras gracilitatis was first 

 found by Dr. A. C. Peale in the Aspen Mountains, south- 

 eastern Idaho, at two places, five miles west of John Gray's 

 Lake, and about fifteen miles west of south from this lake. 

 Professor Hyatt also found it in Wood Canyon, nine miles 

 east of Soda Springs, Aspen Mountains. The writer has 

 also collected numerous specimens of it at the latter local- 

 ity, associated with M. mushbachaniim White, M. a-pla- 

 natu7n White, Flemingites russelli Hyatt & Smith, 

 Pseudosageceras sp. nov., Ussuria sp. nov., Nannites sp. 

 nov., Aspidites sp. nov., Ophiccras sp. nov., Hedenstrcemia 

 sp. nov., and many other forms characteristic of the Lower 

 Trias. The writer has also found this species to be abun- 

 dant in the Meekoceras beds of the Union Wash, near the 

 Union Spring, east side of Owen's Valley, Inyo Range, 

 Inyo County, California, about fifteen miles southeast of 

 Independence, associated with all the above mentioned 

 forms except Fleyningites and Hedenstroefnia. 



The specimens figured in this paper were collected by 

 the writer in Wood Canyon, Aspen Mountains, Idaho. 



Subgenus Gyronites Waagen. 



Type, Gyronites frequens Waagen, Fossils from the Ceratite Formation, 

 1895, p. 292, pi. xxvii, figs. 1-4. 



Evolute, discoidal, laterally compressed, little embracing ; wide, shallow 

 umbilicus ; whorls increasing slowly in height, and covering but a small por- 

 tion of the inner volutions. Venter narrow, either biangular or rounded. 

 Surface smooth, or ornamented only with radial strise and low folds. Body- 

 chamber supposed to be short, but little is known of this character. Septa 

 partly ceratitic, all the saddles and part of the lobes being entire. The 

 external lobe is divided into two unserrated branches by the siphonal saddle. 

 The first lateral lobe is always serrated, the second usually not so ; and there 

 is sometimes a short auxiliary series of denticulations. The internal septa 

 consist of a rather short divided antisiphonal lobe and a single lateral. 



Diener^ says that this group would coincide chiefly with 



1 See Bibliog. 3— p. 3°- 



