338 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 



specimens are compressed and slightly distorted. No traces of the 

 test or outer surface have been seen. 



The glabella is not w^ell preserved in any of the seven specimens 

 before me. One of them is similar in outline to the glabella of Pro- 

 typus hitchcocki (Whitfield)/ but that species is quite unlike B. batis 

 in other characters. One glabella suggests Dorypyge and three the 

 glabella of B. primus. 



The pygidium with its 5 or 6 anchylosed segments is not unlike 

 that of B. haydeni and B. atossa. 



The largest dorsal shield has a length of 38 mm. 



The only associated species is Mesonacis gilberti (Meek) Walcott. 



Formation and locality. — Lower Cambrian: (59P) Millers Moun- 

 tain, 10 miles (16 km.) north of Columbus and west of Belleville, 

 Esmeralda County, Nevada. 



BATHYURISCUS BELESIS, new species 



Plate 50, figs. I, la-i 



The form from locality 4V I referred to "Bathyiiriscus productus" * 

 in my field notes, but comparison shows that it varies in having the 

 anterior half of the glabella more expanded and stronger indications 

 of glabellar furrows. The pleural lobes of the thoracic segments are 

 also terminated in a more abrupt point than those of D. pro'ductus. 

 The adult pygidium is sometimes similar to that of D. productus 

 (pi. 53, fig. 4a), but a pygidium 2 mm. in length has the anchylosed 

 pleural segments as clearly defined as in the type specimens of B. hay- 

 deni, while the larger pygidia have more or less traces of grooves or 

 ridges on the pleural lobes. The pleural ridges on a small pygidium 

 2 mm. in length are more rounded and the furrows narrower than in 

 adult pygidia or in the pygidia of B. belus (pi. 50, figs. 2, 2a-c) or 

 B. anax (pi. 48, figs, i, la-d). 



The cranidium of B. belesis, while similar in form to that of B. 

 belus, differs in its shorter, more anterior palpebral lobe and larger 

 postero-lateral limb and the absence of well-defined glabellar furrows. 



Ejcterior surface unknown. The largest cranidium in the collection 

 has a length of 23 mm. and the largest pygidium 18 mm. 



^ Bull. American Mus. Nat. Hist., Vol. i, 1884, p. 148, pi. 14, fig. 13. 

 ^ Smithsonian Misc. Coll., Vol. 53, No. 5, 1908, Walcott, Cambrian sections of 

 the Cordilleran area, pp. 202-203. 



