NO. 5 CAMBRIAN TRILOBITES 3/1 



Dolichometopus productus differs from D. boccar (pi. 52) in the 

 more anterior position of the palpebral lobes in relation to the length 

 of the glabella, but in the thorax and pygidium they are very closely 

 related. 



For a long- time I considered D. productus as a typical form of 

 Bathyuriscus, but with the present study of all the material the 

 species is referred to Dolichometopus. (See notes under the latter 

 genus.) 



Formation and locality. — Middle Cambrian: (3296, locality of 

 type specimens) Shales in East Canyon above Ophir City, and (3c) 

 about 75 feet (22.9 m.) above the quartzitic sandstones of the Cam- 

 brian at Ophir City, west side of Oquirrh Range; also (152c) Hme- 

 stone at north end of McDowell Mountains, River Bed Station, Old 

 State Road ; (us) shales just above Simpson Spring, about 20 miles 

 (32.2 km.) west-southwest of Vernon, on the stage road from Vernon 

 to Fish Spring; and (sf) siliceous shales above concretionary lime- 

 stone, Onaqui Mountains, 10 miles (16.1 km.) southwest of Grants- 

 ville ; all five in Tooele County, Utah ; also (3v) Chisholm formation, 

 pinkish argillaceous shale, 5.5 miles (8.8 km.) west of Antelope 

 Springs, in Dome Canyon, on road west over the House Range, 

 Millard County; and (3of) Howell formation about 330 feet (101 

 m.) above the Lower Cambrian, in bluish-black, massive limestone 

 forming 1/ of the Howell formation; on east side of Dome Canyon, 

 about 1.5 miles (2.4 km.) from its mouth, and five-sixths of a mile 

 (1.33 km.) west of Antelope Springs; also (31s) Howell formation, 

 about 490 feet (149.4 m.) above the Lower Cambrian in limestone 

 interbedded in pinkish argillaceous shale forming id oi the Howell 

 formation; south side of Dome Canyon, about i mile (1.6 km.) be- 

 low the divide and 3 miles (4.8 km.) west-southwest of Antelope 

 Springs (localities 3V, 3of, 31s are all in Millard County, Utah) ; and 

 (31) Chisholm shale at the Chisholm Mine, southwest slope of Ely 

 Mountains, 3 miles (4.8 km.) northwest of Pioche, Lincoln County, 

 Nevada; also (746) Bright Angel shale 100 feet (32 m.) above 

 Tapeats sandstone; on west side of Cameron trail, about 0.5 mile 

 (0.8 km.) north of Indian Garden Spring; south side Grand Canyon 

 of the Colorado River, Coconino County, Arizona. 



Also (g) Rome formation, shaly sandstone on southeastern slope 

 of ridge i mile (1.6 km.) north of the northwest corner of Harlan 

 Knob, about 4 miles (6.4 km.) northeast of Rogersville [see Keith, 

 1905, areal geology sheet], Hawkins County; and (10) drab shales, 

 western end of Shooks Gap, in Bays Mountains, 10 miles (16.1 km.) 



