PLATE IX—Continued. 
QLENEDDUS HOWELL 2 22 30- secre olewivine = nyo oe = nin amia al =imee fe alate oe alla ele aoa 
Fig. 15. View of a specimen fully developed, excepting the presence of an ocular ridge, 
and the distance of the eyes from the glabella. The genal spines are too short 
in the figure. Natural size. 
15a. Natural-size view of a head hayving.the genal apgles carried forward; eyes 
without au ocular ridge, and the angles of the posterior margin strongly 
marked. 
15b. The head of a young individual, enlarged to four diameters, in which the embry- 
onic features are still more prominent. See plate xxi, figs. 1-9. 
15c. Fragments of thoracic segments associated with this and the following species. 
OULENELLUS GIUBERTISse2 3-222 oc ease wee emcee nee ainlale ele a ate oe (ae eae tate 
Fig.16. View of alargehead, Natural size. See plate xxi, fig. 18. 
16a. Fragment showing the glabella and a portion of the palpebral lobes. Natural size. 
AANOMOCARE! # PARVUM + osc ec tres isso sae alata ae iat a am ella lee ew le ote ese le tattle fila 
Fiz. 17. Enlargement of the specimen described to five diameters. The outline of the pos- 
tero-lateral limb probably extends laterally a little more than in the figure. 
PTYCHUPARIA (?) LINNARSSONI ..---. .----- 22-200 cee one ce enn nee ne enn enna ans nese enen 
Fig.18. View of the broad form of the head, exclusive of the free cheeks, X 2. 
18a. View of the narrow form, similarly enlarged. 
IDICELLOCEPHAT.US# XPANSUS =e ome e serena mays setae ate ie nic eae mee ae eel aetna 
Fig. 19. View showmg the character of the glabella and the peculiar ridges crossing the 
anterior portion of the fixed cheeks, enlarged to one and one-half diameters. 
PTYCHOPARIA (7) PROSPECTENSIS ..---- ..-- 2. - 2-20 <2 w ee sown e See en ene ee nnn eee wenn 
Fig. 20. View of the type specimen, enlarged to three diameters. The furrow crossing the 
glabella at the second pair of glabellar furrows is not seen in the specimen, 
PTYCHOPARIA (PTEROCEPHALUS ?) OCCIDENS .... .--. --------- 20+ 22-2 -- 0 one enn one ene 
Fig. 21. The test is largely exfoliated from the surface of the glabella, and but one pair of 
furrows are shown; figure enlarged to three diameters. 
OGNGIACS) PSPINOSA: 22 2 oso sac a ce om note enn eee leew ele ete le ate elm inal = inform lem oa eaten elie 
Fig. 22. View showing the central portions of the head. Natural size. 
AGRAULOS GLOBOSUS 
Fig. 23. A minute, very convex head, enlarged to four diameters. 
DICELLOCEPHALUS ? QUADRICEPS 
Fig. 24. Small head, enlarged to three diameters. 
DICELLOCEPHALUS OSCEOLA..-...----.---- 
Fig. 25. View of specimen identified with the Wisconsin species. Natural size. 
PTYCHOPARIA ANYTUS 
Fig. 26. Central portions of the head, enlarged three diameters. The fixed cheeks are more 
elevated at the outer termination of the ocular ridges than represented. 
ARETHUSINA AMERICANA 
Fig. 27. View of central portions of head; the ocular ridges are stronger than in the figure; 
enlarged to three diameters. 
PTYCHOPARIA (E.) DISSIMILIS 
Fig. 28. View of fragment showing the central portion of the head. Natural size. 
Page. 
59° 
47 
45. 
46- 
58- 
61 
45 
40: 
62 
5h 
