NO. 2 CAMBRIAN FOSSILS FROM MOHAVE DESERT RESSER 9 



suture is again well marked. The glabella is not quite so far forward, 

 but is also considerably constricted in the center by the convergence 

 of the dorsal furrow. The occipitar furrow marks off a relatively 

 wide occipital ring by means of two straight slits which are also 

 directed slightly backward. The two parts of the third pair of glabel- 

 lar furrows which have a shallow connection across the glabella, are 

 peculiar in the manner of deepening and turning forward at their 

 outer ends into the dorsal furrow. The second and first pairs are 

 as in M. bristolcnsis, as are also the eyes. 



The pleural portion of the third thoracic segment is more than 

 ordinarily enlarged, even for a Mcsoiiacis. 



PAEDUMIAS NEVADENSIS (Walcott), Restricted 



Plate 3, figs. 3-7 



Callavia ? ncvadcnsis Walcott, 1910 (pars), Smithsonian Misc. Coll., Vol. 53, 

 No. 6, p. 285, pi. 38, fig. 12. 



The specific name is here restricted to the incomplete specimen 

 illustrated, and its congeners, cited from the type locality, Eureka 

 District, Nevada (Loc. 52). The removal of this species from 

 Callazna and its reference to Pacdnmias is demanded by the structure 

 of the rim, as pointed out in the preceding generic discussion. 



Since the specimens from Bristol Mountain seem to agree in all 

 respects so far as the incomplete Nevada specimens of P. ncvadcnsis 

 permit comparison, they may be counted as representing a second 

 species common to the two localities. 



Owing to the tapering anterior glabellar lobe, coupled with its dis- 

 tance from the anterior margin, this species cannot well be confused 

 with any other at the California locality, except its close ally P. clarki. 

 Intergenal spines are present. 



PAEDUMIAS CLARKI, new species 



Plate 3, figs. I, 2 



At first this species was referred to one of the forms included in 

 Mesonacis gilhcrti, but closer comparison showed differences from all 

 of them. It seems certain also that some of the specimens referred 

 by authors to the species Mesonacis gilbcrti belong neither to that 

 species nor even to Mesonacis, but are distinct species of Paedumias. 



Compared with P. ncvadcnsis, P. clarki is immediately distinguished 

 by the fuller anterior lobe of the glabella and by the shorter distance 

 between that and the frontal rim. The intergenal spines in P. clarki 

 are too weak to show in the photographs. 



