NO. 5 CAMBRIAN TRILOBITES 389 



spine, and from A. ? granulatus in the absence of coarse granulations. 

 It is the most abundant species, as over 60 specimens were found, 

 while only two of -^4. f granulatus and nine of y^l. f unispintts were 

 collected in the same band of shaly limestone. 



Formation and locality. — Upper Cambrian : Weeks formation ; 

 (son) about 3,750 feet (1,143 "i-) above the Lower Cambrian in 

 shales forming ic of the Weeks formation,^ and (300) about 3,950 

 feet (1,204 n^-) above the Lower Cambrian in the shaly limestones 

 forming 16 of the Weeks formation, both on the north side of Weeks 

 Canyon, about 4 miles (6.4 km.) south of Marjum Pass; also (14V) 

 shales of unknown stratigraphic horizon collected i mile (1.6 km.) 

 south of Rainbow Valley, all in House Range,"" Millard County, Utah. 



ASAPHISCUS ? UNISPINUS, new species 

 Plate 61, fig. I 



This species resembles Asaphiscns ? minor in general appearance, 

 but it has 10 thoracic segments instead of seven, and the eighth seg- 

 ment has a strong median spine on its axial lobe that extends back 

 over the two posterior segments and the pygidium. From A. ? granu- 

 latus it differs in surface, number of thoracic segments, 10 instead of 

 II, and in having the thoracic spine on the eighth instead of the ninth 

 segment. 



Test dense and apparently minutely granulated. 



There are nine specimens of this species in the collection, and all 

 of them were associated in the shaly limestone with A. ? minor and at 

 locality 3011 with A. ? granulatus. 



Formation and locality. — Upper Cambrian : Weeks formation ; 

 (3on) about 3,750 feet (1,143 ^■) above the Lower Cambrian in 

 shales forming ic of the Weeks formation,' and (300) about 3,950 

 feet (1,204 "^0 above the Lower Cambrian in the shaly limestones 

 forming i& of the Weeks formation, both on the north side of Weeks 

 Canyon, about 4 miles (6.4 km.) south of Marjum Pass ; also (14V) 

 shales of unknown stratigraphic horizon collected i mile (1.6 km.) 

 south of Rainbow Valley, all in House Range,' Millard County, Utah. 



Walcott, Smithsonian Misc. Coll., Vol. 53, 1908, p. 178. 

 Idem, pi. 13. 

 Idem, pi. 178. 

 Idem, pi. 13. 



