DESCRIPTION OF GENERA AND SPECIES. 133 



above the white quartzite [see Blackwelder, 19076, p. 92, for general section giving 

 stratigraphic relations], collected in a low bluff on the shore of Tschang-hsing- 

 tau Island, east of Niang-niang-kung, Liau-tung, Manchuria, China. 

 Collected by J. P. Iddings and Li San. 



Ptychoparia ligea Walcott. 

 Plate 12, Figure 1 1. 



Ptychoparia ligea WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxix, p. 79. (Described as a new species 

 as below.) 



Cephalon, exclusive of free cheeks, subquadrilateral in outline, moderately con- 

 vex. Glabella almost of the same width from the posterior margin to the rounded 

 front; three pairs of furrows are faintly but clearly indicated; occipital ring strong; 

 occipital furrow shallow but extended out on the lateral limbs as a strong furrow. 



Fixed cheeks nearly as wide as the glabella; palpebral lobes short and small; 

 palpebral ridges narrow and strongly defined ; frontal limb slightly convex to where 

 it merges into the broad, shallow furrow that extends nearly out to the front margin ; 

 postero-lateral limbs rather long. 



Surface slightly roughened by minute, irregular, raised lines than can only be 

 seen with a strong lens. 



Formation and Locality. Lower Cambrian: (C31) Gray crystalline limestone 

 in the central portion of the Man-t'o shales [Blackwelder, 19070, p. 26 (first list of 

 fossils), and fig. 6 (bed 12), p. 25], at Ch'ang-hia, Shan-tung, China. 



Collected by Eliot Blackwelder. 



Ptychoparia lilia Walcott. 



Plate 12, Figures 12, 120. 



Ptychoparia lilia WALCOTT, 1906, Proc. U. S. Nat. Mus., vol. xxx, p. 588. (Characterized as a new 

 species as below.) 



This species is represented by a single fragment of a cephalon, preserving the 

 glabella, the left fixed cheek, and the frontal limb and rim. It is characterized 

 by the convex glabella, marked by three short, very slightly indicated pairs of 

 glabellar furrows, and the strong, rounded frontal rim separated from the glabella 

 by a very short frontal limb. 



The fixed cheeks are moderately convex and marked by faint, obliquely trans- 

 verse palpebral ridges, palpebral lobes unknown; frontal limb narrow, slightly con- 

 vex; frontal rim strong, rounded thickened in front, and separated from the frontal 

 limb by a shallow, narrow furrow. 



Surface formed by a network of fine, irregular, inosculating, very slightly 

 elevated lines. This surface, when partly worn, has a punctate appearance owing 

 to the shallow places between the lines. The type and only specimen of the 

 cephalon has a length of 5 mm. 



The associated free cheeks have a strong, rather broad border that is continued 

 posteriorly as a strong and rather long spine. 



Formation and Locality. Middle Cambrian: (075) Limestone near the base 

 of the Ki-chou formation [Willis and Blackwelder, 1907, p. 143], 4.5 miles (7.2 km.) 

 south of Wu-t'ai-hien, Shan-si, China. 



Collected by Eliot Blackwelder. 



