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. U.S. Nat. Mus., Cat. No. 
58113. 
Ptychaspis baubo (Walcott) (p. 179). 
2, Fragment of central parts of cranidium. 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. 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-tién limestone, at Ch’au-mi-tién, Shan-tung. U.S. Nat. Mus., Cat. No. 58116. 
3a. Free cheek from same formation and locality as specimen represented by fig.3. U.S. Nat. Mus., 
Cat. No. 58117. 
3b. 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-tién lime- 
stone, two-thirds of a mile (1.1 km.) west of Tsi-nan, Shan-tung. U.S. Nat. Mus., Cat. No. 
58121. 
Ptychaspis ? sp. undt. (c) 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 C67, Upper Cambrian, a 
fragment of limestone in the drift west of the wset city gate, Tsi-nan, Shan-tung. Fig. 8 
is from Locality C 38, Upper Cambrian, the Ch’au-mi-tién limestone, 9 miles (14.5 km.) north 
of Sin-t’ai-hién, Shan-tung. U.S. Nat. Mus., Cat. Nos. 58122 and 58123, respectively. 
Ptychaspis bella Walcott (p. 180). 
9. Type specimen, showing portions of central parts of cephalon; and side outline of same, X 2. From 
Locality C74, Upper Cambrian, Ki-chéu limestone, east of Fang-lan-chén, Shan-si. U. S. 
Nat. Mus., Cat. No. 58124. 
Ptychaspis cacus Walcott (p. 181). 
10. Fragment of free cheek associated with fig. 11, *X 3. U.S. Nat. Mus., Cat. No. 58125. 
11. Type specimen showing portions of central parts of cephalon, and side view of same. Natural size. 
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 tuberculated outer test has been exfoliated, & 1.25. 
U. S. Nat. Mus., Cat. No. 58294. 
12a and 12b. Side and front views of specimen represented by fig. 1. 
12c. 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. 168). 
13. Dorsal view and side outline of cranidium, X 4. From Locality 35r, Middle Cambrian, Fu-chéu 
series, Liau-tung, Manchuria. U.S. Nat. Mus., Cat. Ne. 57588. 
Solenopleura beroe Walcott (p. 168). 
14. Dorsal view and side outline of a small cranidium, X 3. From Locality 35n, Middle Cambrian, 
Fu-chou series, Liau-tung, Manchuria. U.S. Nat. Mus., Cat. No. 58066. 
14a. 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-tién 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 limestone at Ch’au-mi-tién, Shan-turg. U.S. Nat. Mus., Cat. No. 
58072. 
16a. Associated free cheek, doubtfully referred to this species. U.S. Nat. Mus., Cat. No. 58073. 
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