GEOLOGICAL SURVEY OF THE TERRITORIES. 465 



12. Bathyunis, or DiJcelocephahts .. .'Fragments. 



13. Batliyurellus [Dikelocephalus (^) 



truncatus, Meek Described iu this report. Occurs also 



at Flat-Head Pass.- 

 14z. Asaphus (Megalaspis (?) gonio- 



cercus, Meek Described in this report. Occurs at 



Flat-Head Pass. 



WEST FACE OF BIG HORN MOUNTAIN, HEAD BUFFALO FORK. 



Names. Remarks. 



1. Conocoryphe, and, perhaps, Bilce- 



locephalus* Mere fragments. 



CAEBOMFEROUS SPECIES. 



OUTLET OF MYSTIC LAKE, MONTANA. 



Names. Remarks. 



1. Zaphrentis A small species. 



2. Zaj)Jirentis Fragment of a large species appar- 



ently of this genus. 



3. Ftilodictya [Stictopora'l) dicty- 



ota, Meekf 



4. Pfylodictya A merely branching species. 



5. Fenestella One or two species. 



Q. Hemipronitescrenistria,'Phil\i})s. Blather more finely striated than 



usual. 



7. Chonetes '. An abundant medium sized species 



with very fine, dichotomous, radi- 

 ated strii3e, crossed by very minute 

 concentric strise; spines of cardi- 

 nal margin, five on each side of 

 beak. 



8. Productm longisjpinus, Sowerby .A small form, apparently agreeing 



"with Sowerby's species. 



9. Prodv/3tus scabriculus, Martin (?). Specimens fragmentary. 



10. Eliynclionella. 



11. SpirifeVj {Martinia) Of medium size. 



12. Spirifer {Martinia) ^inmto, Mar- 



tin. 



13. Spirifer Similar to some varities of 8. incre- 



hescens, Hall, which Mr. Davidson 

 thought not distinct from S. Msul- 

 cata. 



" The only part in the collection certainly kn'own to belong to this species is the 

 pygidium. This has much the general appearance of the corresponding part of a trilo- 

 bite, figured by Mr. Billings, under the name of Asaphus quadraticatidatus, (Paleont., 

 Canada, p. 271, Fig. 258,) but its lateral margins are straighter and its mesial lobe 

 proportionally longer, with only three to five segments that i)ass straight across, in- 

 stead of eight or nine arching forward. Its lateral lobes show three or four short seg- 

 ment, instead of only one, while they and the lateral margins show no traces of the 

 strife seen on Mr. Billings's species. Its lateral and posterior flattened margins are 

 more suddenly defined from the swell of the lateral lobes. 



t An anastomosing species, with divisions about 0.10 to 0.12 inch in breadth, by 0.04 

 to 0.0.5 inch in thickness, and connecting so as to form a reticulated structure, with 

 fenestrules of a more or less oval form, about 0.24 inch in length by 0.16 inch in breadth. 

 Pores small, with slightly raised ma; gins, having the usual quincuncial arrangement, 

 and forming six to eight longitudinal rows; non-poriferous margins rather sharp, and 

 of moderate breadth. 



30 G s ' 



