Layral Sfiujc.s of Triloliife.s. — litfcrher. 193 
31. Packard, A. S. Jr., ISaS. -A Monograph of North American Phyl- 
lopod Crustacea. Twelfth An. Rept. U. S. Geol. and Geog. Sur- 
vey. 
32. Salter, J. W.. 1866. -A Monograph of Briti.sh Trilol)ites. Part III. 
Palaeont. Soc. London, vol. xviii. 
as. Walcott, C. D., 1877. Notes upon the Eggs of Trilobites. Pub- 
lished in advance of 31st Rept. N. Y. State Mus. Nat. Hist. 
34. 1879. Fossils of the Utica Slate and Metamorphoses of Tri- 
arthrus Becki. Printed in advance of Trans. Albany Inst., vol. x. 
35. 1886. — Second Contribution to the Stvidies on the Cambrian 
Faunas of North America. Bull. U. S. Geol. Surv.. No. ,30. 
36. 1890. — The Fauna of the Lower Cambrian or Olenellus Zcme. 
Tenth An. Rept. Director U. S. Geol. Surv., 1888-'89. 
37. Woodward, Henry, 1895. Some Points in the Life-history of the 
Crustacea in Early Palaeozoic Times. Anniversary Address of the 
President. Qviar. Jour. Geol. Soc. Lond.. vol. li. 
X. Exi'LANATiox or Plates. 
PLATE VIII. 
Figure 1. Soleitoplenra i-obhi Hartt : after Matthew. Anaprotaspis 
stage: showing oVjscurely annulated axis. x.3(). St. John group, Cam- 
brian, New Brunswick. 
Figure 2. Liostrdciis oindigondidiiiis Hartt : after Matthew. Ana- 
protaspis stage ; the neck lobe is the only one distinctly marked. x23. 
Cambrian, New Brunswick. 
Figure 3. Ptycliopan'a linuar.ssoni W-d'n:ott: after Matthew. Ana- 
protaspis stage ; axis slender, slightly annvilated : pygidium defined l)y 
transverse furrow. x30. Cambrian, New Brunswick. 
Figure 4. PtychopaiHa linnarssoni Walcott: after Matthew. Pro 
taspis representing a later moult than the preceding, and showing 
stronger annulations on the axis, with an additional one on the pygidi 
um. x25. C^ambrian, New Brunswick. 
Figure 5. Ptycliopaiia kingi Meek. Anaprotas|)is or early stage ; 
showing obscvn-ely defined characters, partly due to the fact that the 
specimen is a cast. x45. CamVjrian, Nevada. 
Figure 6. Ptyc]ioparia kingi Meek. A later stage (metaprotaspis) : 
showing the strongly annulated axis, the eye-line, the free-cheeks in 
eluding the genal angles, and two segments on the pygidium. x45. 
Cambrian, Nevada. 
Figure 7. Ptycliop(iri<( kingi Meek : after Walcott. An adult spec- 
imen. This and the other figures of adult individuals are represented 
in outline, with the free-cheeks shaded, to bring out more strongly the 
changes in the structure of the cephalon. xl^. Cambrian, Utah. 
Figure 8. S<io Jn'rsnta. Barrande : after Barrande. Anaprotaspis 
stage ; showing obscurely the limits of the pygidium, the eye-line, and 
the nearly cylindrical glabellar axis, expanding on the frontal margin. 
This and the two following specimens are preserved as casts. .x30. Cam- 
brian, Bohemia. 
