DESCRIPTION OF PLATE 16. 



Chuangia nais Walcott (p. 171). 



1. Dorsal view and side outline of a fragmentary specimen of the central parts of a ccphalon. Natural 



size. From Locality C 64, Upper Cambrian, Kiu-lung group, southwest of Yen-chuang, Shan- 

 tung. U. S. Nat. Mus., Cat. No. 57608. 



Chuangia fragmenta Walcott (p. 171). 



2. Dorsal view and side outline of a fragmentary specimen of central parts of a cephalon, X i .5. From 



Locality C61, Upper Cambrian, Kiu-lung group, southwest of Yen-chuang, Shan-lung. U.S. 

 Nat. Mus., Cat. No. 57607. 



Menocephalus abderus (Walcott) (p. 17.0. 



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



Locality CIO, Middle Cambrian, Ch'ang-hia limestone, at Ch'ang-hia, Shan-Uing. U. S. 

 Nat. Mus., Cat. No. 58076. 



Menocephalus acanthus Walcott (p. 173). 



4. Type specimen, showing portions of cential parts of cephalon; and side outline of same, X 3. From 



Locality C22, Middle Cambrian, Ch'ang-hia limestone, at Ch'ang-hia, Shan-tung. U. S. 

 Nat. Mus., Cat. No. 58077. 



4<t. Fragment showing form of palpebral lobe and postero-lateral glabellar lobes of a cephalon asso- 

 ciated with the specimen represented by fig. 4, X 4. (C22.) U. S.Nat. Mus., Cat. No. 58078. 



46. Associated pygidium, X 3. (C22.) U. S. Nat. Mus., Cat. No. 58079. 



Levisia adrastia (Walcott) (p. 177). 



5. Top and side views of type specimen, X 4. From Locality 030, Middle Cambrian, Ch'ang-hia 



limestone at Ch'ang-hia, Shan-tung. U. S. Nat. Mus., Cat. No. 58084. 

 5U. Associated fragment of a ccphalon. (C30.) U. S. Nat. Mus., Cat. No. 58085. 



Menocephalus ? depressus Walcott (p. 176). 



6. Top and side views of type specimen, X 4. From Locality C 56, Upper Cambrian, Ch'au-mi-tien 



formation west of Tsi-nan, Shan-tung. LI. S. Nat. Mus., Cat. No. 58080. 



da. Free cheek (X 2) associated with this species at Locality 049, Upper Cambrian, Ch'au-mi-tien 

 limestone, west-southwest of Ch'au-mi-tien, Shan-tung. U. S. Nat. Mus., Cat. No. 58081. 



Menocephalus ? sp. undt. Walcott (p. 176). 



7. A small cephalon doubtfully referred to this genus, X 3. From Locality C 1C, Middle Cambrian, 



Kin-lung group, southwest of Yen-chuang, Shan-tung. U. S. Nat. Mus., Cat. No. 58082. 

 717. Associated fragment of glabella and fixed cheeks, X 4. U. S. Nat. Mus., Cat. No. 58083. 



Menocephalus acidalia Walcott (p. 174). 



S. Type specimen showing portions of central parts of cephalon; and side outline of same, X 4. From 

 Locality C30. Middle Cambrian, Ch'ang-hia limestone, at Ch'ang-hia, Shan-tung. U. S. 

 Nat. Mus., Cat. No. 58086. 

 8u. Associated free cheek, X 1.5. U. S. Nat. Mus., Cat, No. 58087. 



Menocephalus agave Walcott (p. 176). 



9. Top and side views of type specimen, X 3. From Locality C30, Middle Cambrian, Ch'ang-hia 



limestone, at Ch'ang-hia, Shan-tung. U. S. Nat. Mus., Cat. No. 58088. 



Menocephalus acerius Walcott (p. 174). 



10. Top and side views of type specimen, X 2. From Locality CIS, Middle Cambrian, Ch'ang-hia 



limestone, east of Ch'ang-hia. Shan-tung. U. S. Nat. Mus., Cat. No. 58089. 



io<i. Free cheek, X 2. Associated with fig. 10. This occurs on a piece of limestone beside the pygid- 

 ium of Crepicephalus damia, plate 13, fig. 14. U. S. Nat. Mus., Cat. No. 58090. 



Menocephalus acis Walcott (p. 175). 



11. Top and side views of type specimen, X 4. From Locality C35, Middle Cambrian, Ch'ang-hia 



limestone, at Ch'au-mi-tien, Shan-tung. U. S. Nat. Mus., Cat. No. 58091. 



Menocephalus admeta Walcott (p. 175). 



12. Top and side views of a minute cephalon doubtfully referred to this genus, X 6. F'rom Locality 



C22, Middle Cambrian, Ch'ang-hia limestone, at Ch'ang-hia, Shan-tung. U. S. Nat. Mus., 

 Cat. No. 58092. 



Ptychaspis calchas Walcott (p. 183). 



13 (Natural size) and 130 (X 1.5). Fragmentary specimens of glabella and palpebral lobes. From 

 Locality C41, Upper Cambrian, Ch'au-mi-tien limestone, southwest of Ch'au-mi-tien, Shan- 

 tung. U. S. Nat. Mus., Cat. Nos. 58093 and 58094, respectively. 



Ptychaspis callisto Walcott (p. 183). 



14. Type specimen showing portions of central parts of cephalon; and side outline of same, X 1.5. 



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



U. S. Nat. Mus., Cat. No. 58095. 

 140. Associated free cheek, X 1.5. U. S. Nat. Mus., Cat. No. 58096. 



259 



