CAMBKIAN FOSSILS. 441 



Carabrian fauna of Nevada or British Columbia. There are no indications 

 of the Lower Cambrian or Olenellus fauna. The upper-division fauna is 

 also strongly related in its Brachiopoda to the Mississippi Basin fauna. It 

 includes the following species: 



Obolus (LiDgi\lella) desideratus. 

 Dicellornus nanus. 

 Billingsella coloradoensis. 

 Orthis rernnicha. 

 Orthis saDdbergi. 

 Ptychoparia (E.) affinis. 

 Ptychoparia llanoensis? 

 Ptychoparia (sp. undet.). 

 Ariouellus levis. 



The species common to the Cambrian fauna of the Park and the Upper 



Mississippi Valley are as follows: 



Billingsella coloradoensis. 



Orthis remnicha. 



Orthis sandbergi. 



Platyceras primordialis. 



Hyolithes primordialis. 



Ptychoparia (Louchocephalus) hamulus ? 



Ptychoparia (Louchocephalus) wisconsensis. 



Ptychoparia (?) diademata. 



Of other species, Agnostus Helens and Agnostus interstrictus are closely 

 related to A. josepha, and it is quite probable that Dice'llomus nanus and 

 Ptychoparia antiquata will be found in the Upper Mississippi Valley fauna. 



Billingsella coloradoensis, Orthis remnicha, and Crepicephalus texanus are 

 found in the Cambrian rocks of central Texas, and Ptychoparia antiquata and 

 Crepicephalus texanus occur in the Middle Cambrian of northern Alabama. 



It is anticipated that a large addition will be made to this fauna when 

 the Cambrian collections from the Gallatin Valley north of the Yellowstone 

 National Park are studied. The purpose of this paper is to describe and 

 illustrate only the species found within the limits of the Park and the 

 immediately adjoining Absaroka Range on the east. 



Preliminary examinations of the collections were made from year to 

 year as the specimens were brought from the field and reports were made 

 to Mr. Arnold Hague. When it was found possible to make a detailed study, 

 I requested Mr. G H. Girty to prepare the brachiopods contained in the col- 

 lection, and I am indebted to him for assistance rendered in this direction. 



