370 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 



Bathyuriscus productus Grabau and Shimer, 1910, North American Index 

 Fossils, Vol. 2, p. 287, fig. 1591. (Brief description and figure of cran- 

 idium and pygidium after Walcott.) 



• The head and pygidium of this species are much Hke those of the 

 type species of Dolichometopus, D. suecicus. The thorax has seven 

 segments, the pleurae of which have a rather strong furrow that 

 extends from the anterior inner side diagonally across the segment 

 ending about midway where it begins to curve backward to its rather 

 sharp falcate termination. 



Specimens of the dorsal shield from the type locality vary from 

 50 to 60 mm. in length, and cranidia from the Pioche Mountains, 

 Nevada, indicate a length of 75 mm. 



The species has a wide geographic distribution and occurs in a 

 variety of rocks. The type specimens are from a very finely arena- 

 ceous, Middle Cambrian shale found in East Canyon, Oquirrh Range, 

 Utah. They are compressed and flattened in the shale, but a fairly 

 good conception of the species may be obtained from them. The 

 specimens from the Chisholm shale near Pioche, Nevada, are some- 

 what better preserved, but they do not retain the original test, and the 

 surface markings are lost with the exception of the fine striae on the 

 surface of the doublure of the pygidium. 



Another interesting locality is at the north end of the McDowell 

 Mountains at River Bed Station, where a form closely allied to this 

 occurs in a Hmestone. It was identified as Bathyiirellus wheeleri,^ 

 but the head is that of Dolichometopus and it has the thorax and 

 pygidium of the character of that of D. productus as it appears when 

 not flattened in shale. 



The species is represented in the Bright Angel arenaceous shales 

 of the Grand Canyon, Arizona, by a number of entire dorsal shields 

 (pi. 53, figs. 4, 4a). These appear to have the elongate palpebral 

 lobe and relatively narrow glabella of specimens from the type local- 

 ity, and the thorax and pygidium are essentially the same. 



The specimens from the southern Appalachians are preserved in 

 argillaceous and siliceous shales and limestone. As far as the ma- 

 terial available afifords the means for comparison, they appear to 

 belong with D. productus or a closely related species. A broken 

 specimen from a siHceous shale (locality 10) has seven thoracic seg- 

 ments, and entire associated cranidia and pygidia appear to be similar 

 to the specimens in the shales of the type locality of the species. The 

 specimens in the limestone (locality 14) are strongly convex. 



^ Geog. and Geol., Expl. West looth Meridian, Vol. 3, 1875, p. iSi 



