DESCRIPTION OF PLATE 17. 



Ptychaspis ? sp. undt. (a) Walcott [see plate 21, fig. 14] (p. 186). 



1. Fragment of free cheek, natural size, from Locality C64, Upper Cambrian, Kiu-lung group, 2.7 miles 



(4.3 km.) southwest of Yen-chuang, Sin-t'ai district, Shan-tung. IT. S. Nat. Mus., Cat. No. 

 58113- 



Ptychaspis baubo (Walcott) (p. 179). 



2. Fragment of central parts of cranidium. Natural size. From Locality C 64, Upper Cambrian, Kiu- 



lung group, 2.7 miles (4.3 km.) southwest of Yen-chuang, Sin-t'ai district, Shan-tung. U. S. Nat. 

 Mus., Cat. No. 58114. 

 2a. Associated free cheek. U. S. Nat. Mus., Cat. No. 58115. 



Ptychaspis brizo (Walcott) (p. 181). 



3. Anterior part of central portion of cranidium; with side outline. From Locality C38, Upper Cam- 



brian, Ch'au-mi-tien limestone, at Ch'au-mi-tien, Shan-tung. U. S. Nat. Mus., Cat. No. 58116. 

 30. Free cheek from same formation and locality as specimen represented by fig. 3. U.S.Nat. Mus., 



Cat. No. 58117. 



36. Associated pygidium, X 2. U. S. Nat. Mus., Cat. No. 58118. 

 4 (X 1.5) and 5 (natural size). Large free cheeks associated with fig. 3. U. S. Nat. Mus., Cat. Nos. 



58119 and 58120, respectively. 



Ptychaspis ? sp. undt. (b) Walcott [see plate 21, fig. 15] (p. 186). 



6. Fragment of large free cheek (natural size) from Locality C54, Upper Cambrian, Ch'au-mi-tien lime- 

 stone, two-thirds of a mile (i.i km.) west of Tsi-nan, Shan-tung. U. S. Nat. Mus., Cat. No. 

 58121. 



Ptychaspis ? sp. undt. (r) Walcott (p. 186). 



7 (X 2, C67) and 8 (X 2, C33). Two free cheeks from widely separated localities that are of the same 

 general type. The specimen represented by fig. 7 is from Locality 067, Upper Cambrian, a 

 fragment of limestone in the drift west of the wset city gate, Tsi-nan, Shan-tung. Fig. 8 

 is from Locality 033, LTpper Cambrian, the Ch'au-mi-tien limestone, 9 miles (14.5 km.) north 

 of Sin-t'ai-hien, Shan-tung. U. S. Nat. Mus., Cat. Nos. 58122 and 58123, respectively. 



Ptychaspis bella Walcott (p. 180). 



t). Type specimen, showing portions of central parts of cephalon; and side outline of same, X 2. From 

 Locality C74, Upper Cambrian, Ki-chou limestone, east of Fang-lan-chon, Shan-si. U. S. 

 Nat. Mus., Cat. No. 58124. 



Ptychaspis cacus Walcott (p. :8i). 



10. Fragment of free cheek associated with fig. n, X 3. U. S. Nat. Mus., Cat. No. 58125. 



1 1 . Type specimen showing portions of central parts of cephalon, and side view of same. Natural ?ize. 



From Locality C64, Upper Cambrian, Kiu-lung group, southwest of Yen-chuang, Shan-tung. 

 U. S. Nat. Mus., Cat. No. 58126. 



Solenopleura holometopa Angelin (p. 167). 



12. Dorsal view of a cranidium from which the tuberculnted outer test has been exfoliated, X 1.25. 



U. S. Nat. Mus., Cat. No. 58294. 



I2<i and 126. Side and front views of specimen represented by fig. i. 



i2r. Enlargement of granulated surface on free cheek, X 3. U. S. Nat. Mus., Cat. No. 58295. 

 The specimens illustrated are from the type locality of the species, Andrarum, Sweden. 



Solenopleura chalcon Walcott (p. i6S). 



13. Dorsal view and side outline of cranidium, X 4. From Locality 35r, Middle Cambrian. Fu-chou 



series, Liau-tung, Manchuria. U. S. Nat. Mus., Cat. Nc. 57588. 



Solenopleura beroe Walcott (p. 168). 



14. Dorsal view and side outline of a small cranidium, X 3. From Locality 35 n, Middle Cambrian, 



Fu-chou series, Liau-tung, Manchuria. U. S. Nat. Mus., Cat. No. 58066. 

 140. Dorsal view of a cranidium associated with that represented by fig. 14, X 3. U. S. Nat. Mus., 



Cat. No. 58067. 

 17. Type specimens showing portion of central parts of cephalon; and side outline of same, X 5. 



From Locality C64, Upper Cambrian, Ch'au-mi-tien formation, southwest of Yen-chuang, 



Shan-tung. U. S. Nat. Mus., Cat. No. 58068. 



Solenopleura agno Walcott (p. 167). 



15. Type specimen showing portions of central parts of cephalon; and side outline of same, X 3. 



From Locality C25, Middle Cambrian, Ch'ang-hia formation at Ch'ang-hia, Shan-tung. 

 U. S. Nat. Mus., Cat. No. 58069. 



Solenopleura intermedia (Walcott) (p. 169). 



16. Small cephalon, showing scattered tubercles on the surface, X 3. From Locality C51, Middle 



Cambrian. Ch'ang-hia lirrestone at Ch'au-mi-tien, Shan-tung. U. S. Nat. Mus., Cat. No. 

 58072. 



160. Associated free cheek, doubtfully referred to this species. U. S. Nat. Mus., Cat. No. 58073. 



261 



