590 PROCEEDINGS OF THE XATIOXAL MUSEUM. 



ward toward the center; dorsal furrow rather .sharply defined at the 

 sides and shallow in front of the glabella. 



Plxed cheek narrow, and elevated into a ridge opposite the palpe- 

 bral lobe, which is separated b}- a narrow, curved furrow; ocular ridge 

 low, narrow, and passing* obliquely from the anterior end of the pal- 

 pebral lobe to the antero-lateral angle of the glabella; postero-lateral 

 limb narrow, about as long as the width of the front of the glabella, 

 and marked b}^ a rather strong furrow within an elevated, narrow 

 posterior rim; frontal limb narrow, merging in front into the narrow, 

 slight furrow produced ))y the union of the frontal limb and frontal 

 rim; frontal rim of medium width, moderately convex, and rounding 

 down to meet the frontal limb. 



Surface appears to be minutely and irregularly punctate under a 

 lens of moderate power. Under a strong lens it is shown to be formed 

 by a network of irregularly inosculating, raised lines, that are so 

 interrupted in places as to give a granular appearance to the surface. 

 The largest head in the collection has a length of 5 mm. 



OhsemHitionx. — This species is most nearly related to Ptychoparia 

 coinus (p. 586); it differs in having a proportionately shorter glabella, and 

 a more convex, thickened frontal rim. It differs from Ptychoparia 

 {Llostracii.^) tlira.so Walcott" in its shorter frontal limb and propor- 

 tionally longer glabella. 



This species is associated with Ptychoparia comus and Solenopleura 

 fauperata (p. 593). 



Formation and locality. — Middle Cambrian, oolitic limestone; 4 

 miles south-southwest of Tung-yii-chcin, Shen-si, China. 



Collected by Eliot Blackwelder. 



PTYCHOPARIA VESTA, new species. 



Of this species the central portions of the head are known, and asso- 

 ciated free cheeks and pygidia. The parts of the head preserved show 

 it to have been moderatel}" convex, and semicircular in outline. Gla- 

 bella convex," not very prominent, broadly truncato-conical in outline; 

 antero-lateral angles rounded, front gently curved; between the l)ase 

 and front the sides are slightly incurved at a point about two-thirds 

 the distance from the base to the front; three pairs of glabellar fur- 

 rows that extend al)out one-half the distance from the sides toward the 

 center are faintly impressed; occipital furrow narrow, shallow, and 

 transverse; occipital ring narrow at the sides, widening toward the 

 center where the surface is on the i)lane of the glabella; dorsal furrow 

 narrow and clearl}- defined at the sides, and shallow in front of the 

 glal)ella. 



Fixed cheeks a little more than one-half the width of the glabella, 

 nearly flat opposite the palpebral lobes, curving gently downward pos- 



«Proc. U. S. Nat. Mus., XXIX, 1905, p. 85. 



