NO. 3 UPPER CAMBRIAN TRILOBITE FAUNAS — RASETTI 127 



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erous meraspid cranidia in various stages, X7.5. 2, 3, Dorsal and 

 frontal views of cranidium, X3. 4, Cranidium, X4. 7, Free cheek, x2. 

 8, 17, Free cheeks, x3. 9, Hypostome, x5. 10-12, Pygidia, X4 (all 

 above specimens from collection cnw/20) ; U.S.N.M. 144640, para- 

 types. 13-15, Dorsal, lateral, and frontal views of cranidium, x2 (coll. 

 cnu/1) ; U.S.N.M. 144641, paratype. 16, Pygidium, x3 (coll. cnu/7) ; 

 U.S.N.M. 144642, paratype. 18, Pygidium, x3 (coll. cnv/7) ; U.S.- 

 N.M. 144642, paratype. 



Plate 21 



Figs. 1-9. Dytremacephalus angulatus Rasetti, n. sp 98 



1-3, Dorsal, lateral, and frontal views of cranidium, x5 (coll. cnw/14) ; 

 U.S.N.M. 144686, holotype. 4, Cranidium, x5. 7, Pygidium, x5 (coll. 

 cnw/14) ; U.S.N.M. 144687, paratypes. 5, Free cheek, x5. 6, 8, Py- 

 gidia, x5 (coll. cnx/1) ; U.S.N.M. 144688, paratypes. 9, Rubber cast 

 of impression of thorax and pygidium, x4 (coll. U.S.G.S. 2969) ; 

 U.S.N.M. 144689, paratype. 



Figs. 10-13. Dytremacephalus strictus Rasetti, n. sp 102 



10, Cranidium, xS (coll. U.S.G.S. 2970) ; U.S.N.M. 144692, holotype. 

 11-12, Cranidia, xS. 13, Exfoliated cranidium, xS (coll. U.S.G.S. 

 2970) ; U.S.N.M. 144693, paratypes. 



Figs. 14-28. Paraphelaspis vigilans Rasetti, n. gen., n. sp 97 



14-16, Dorsal, lateral, and frontal views of cranidium, x6 (coll. ens/ 

 20) ; U.S.N.M. 144683, holotype. 17, Exfoliated free cheek, x4. 18, 

 19, Frontal and dorsal views of cranidium, X7.5. 20, 21, Dorsal and 

 frontal views of cranidium, x5. 22, Cranidium, X7.5. 23, Exfoliated 

 cranidium, x5. 24, 25, Free cheeks, X5 (coll. cns/20) ; U.S.N.M. 

 144684, paratypes. 26, 27, Lateral and dorsal views of cranidium, x7.5. 

 27, Cranidium, X4 (coll. cnr/4) ; U.S.N.M. 144685, paratypes. 



