DESCRIPTION OF GENERA AND SPECIES. 135 



Of the species from China of this subgenus, P. (E.) theano (Walcott) [plate 13, 

 fig. 2], P. (E.) bromus (Walcott) [fig. 3], and P. (E.) eriopia (Walcott) [fig. 4] have 

 the posterior elongate palpebral lobe. In P. (E.) mantoensis (Walcott) [fig.i] and 

 P. (E.) constricta (Walcott) [fig. 5] the palpebral lobe is much like that of Ptycho- 

 paria in its position. 



Stratigraphic Range. Ptychoparia (Emmrichella) mantoensis and P. (E.) con- 

 stricta occur at the summit of the Lower Cambrian; P. (E.) eriopia and P. (E.) 

 theano at the base of the Ch'ang-hia formation of the Middle Cambrian; and P. 

 (E.) bromus at about the same horizon in the Kiu-lung formation. 



Ptychoparia (Emmrichella) bromus (Walcott). 



Plate 13, Figure 3. 



Ptychoparia ? bromus WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxix, p. 76. (Described as a new 

 species essentially as below.) 



This species is represented by the central portions of the cephalon, exclusive 

 of the free cheeks. Glabella moderately convex, truncato-conical, rounded in front, 

 and apparently without furrows; occipital furrow transverse and clearly defined; 

 occipital ring strong and moderately convex; dorsal furrow broad and shallow. 



Fixed cheeks nearly as wide as the glabella opposite the palpebral lobe; they 

 rise slightly from the dorsal furrow to the palpebral lobe, and slope gently back- 

 ward to the postero-lateral limb and forward to the frontal limb; palpebral lobe 

 narrow, about one-third the length of the cephalon; palpebral ridge rounded and 

 faintly defined ; frontal limb of medium width, slightly convex, and sloping gently 

 down to a rounded furrow that separates it from the flattened frontal rim, which is 

 about one-half as wide as the frontal limb. 



The surface is slightly roughened by minute granulations, as seen with the 

 aid of a strong lens. 



The largest specimen of the cephalon in the collection has a length of 7 mm. 



This species is characterized by the rounded, smooth appearance of the glabella, 

 fixed cheeks, dorsal furrow, and frontal limb. 



Formation and Locality. Middle Cambrian: (0(5) Thin, platy limestone in 

 the upper shale member of the Kiu-lung group [Blackwelder, 190711, pp. 37 and 41 

 (second list of fossils), and fig. 10 (bed 12), p. 38], 2.5 miles (4 km.) southwest of 

 Yen-chuang, Sin-t'ai district, Shan-tung, China. 



Collected by Eliot Blackwelder. 



Ptychoparia (Emmrichella) constricta (Walcott). 

 Plate 13, Figures 5, 517. 



Ptychoparia conslricta WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxix, p. 77. (Described as a new 

 species.) 



The convex central portions of the cephalon, exclusive of the free cheeks, are 

 subquadrilateral in outline. Glabella subcylindrical, narrowing slightly toward the 

 front, with only faint indications of glabellar furrows; occipital furrow narrow, 

 clearly defined, but shallow ; occipital ring strong, narrow at the sides and broad at 

 the center. 



Fixed cheeks about as broad as the glabella ; palpebral ridges strong and merg- 

 ing into the rather long palpebral lobes; frontal limb well defined by the palpebral 

 ridges and narrow, slightly flattened frontal rim. 



Surface slightly roughened by minute, irregular, raised lines. 



Formation and Locality. Lower Cambrian: (C3) Lower part of the Man-t'o 

 shale formation [Blackwelder, 190711, p. 28 (list of fossils at bottom of page), and 



