NO. 1458. CAMBRTAX FAUXAS OF CHINA— WALCOTT. 591 



teriorly to the posterior furrow, and rather abruptly downward to 

 merge into the frontal limb; palpebral lobes a little less than one-half 

 the length of the head, narrow, and separated from the fixed cheeks 

 by rather strong, curved furrows; ocular ridge low, rather strong, 

 and extending obliqueh^ forward from the anterior edge of the pal- 

 pebral lobe to the side of the glabella, just back of its antero-lateral 

 angle; frontal limb short, gently convex, and sloping down from the 

 front of the glabella to the rounded furrow formed b}" its merging 

 with the frontal rim; frontal rim nearly flat and rising at a low angle 

 from the furrow. 



Surface smooth to the unaided eye, finely punctate under a strong 

 lens. The largest head referred to this species has a length of 9 mm., 

 and the specimen selected as the type, a length of 4 mm,, with a width 

 at the outer edge of the palpebral lobes of 6 mm. 



The associated free cheek has the same type of nearly flat rim as 

 the rim in front of the glabella; this is extended at the postero-lateral 

 angle into a moderately strong, sharp spine; the bodj^ of the cheek 

 rises to the base of the eye lobe with very little convexity; it is sepa- 

 rated from the lateral and posterior borders by a shallow furrow; the 

 surface is marked by irregular lines radiating from the base of the 

 eye lobe toward the furrow within the outer margin. 



The associated pygidium has a planulate border that merges into the 

 slope of the pleural lobes; axis convex, about three-fourths the length 

 of the pygidium, and marked by three shallow transverse furrows that 

 are continued across the pleural lobes out onto the planulate margin. 



Observations. — The general form of the head of this species is much 

 like that of Piychyparia impar Walcott." It differs in having a flatter 

 frontal rim, less convex frontal limb, stronger glabellar furrows, and 

 larger palpebral lobes. From Ptychojjaria {Liostracrts) megalurus 

 Dames* it diflfers b}^ having a more subquadrangular glabella, and 

 larger palpebral lobes. 



Formation and locality. — Middle Cambrian, lower portion of oolitic 

 limestone series; 4 miles east of Fang-lan-chon, Shan-si, China. 



Collected by Eliot Blackwelder. 



PTYCHOPARIA, species undetermined. 



This form is represented by a minute head 1.25 nun. in length. It 

 has an elongate glabella of the type of Pfychoparia tlieaiio Walcott,'' 

 but its palpebral lobes are longer than in that species. It may be the 

 young of Ptychoparia aclis Walcott.'^ 



A small head about 2 mm. in length of about the same character as 



«Proc. U. S. Nat. Mus., XXIX, 1905, p. 78. 



bLiostracus megalurus Dames, 1883, China, Riehthofen, IV, p. 20. 



^•Proc. U. S. *Nat. Mus., XXIX, 1905, p. 82. 



<^Idem, p. 75. 



