398 Prof. F. M‘Coy on the Classification of 
Faceted pleure of Trilobites. 
a, Calymene; 6, Ellipsocephalus ; c, Asaphus ; d, Phacops; e, Odontochile ; 
f, Dysplanus; g, Illenus; h, Forbesia; 7, Homalonotus; 4, Trimero- 
cephalus. 
MM Hii IL a nig Tjene tS an 7 
Thy 
W 
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i 
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12 tI 
I eae 
9 end \ ; le 
SS 
Non-faceted pleure of Trilobite s. 
1, Ogygia; m, Lichas; n, Bronteus ; 0, Ampyx; p, Harpes; g, Conocepha- 
lus; r, Paradoxides; s, Zethus; ¢, Crypheus; u, Acidaspis; v, Stau- 
rocephalus; w, Olenus; x, Trinucleus; y, Ceraurus. 
a 
wm, 
a il 
4, Harpedine ; 5. Agnostine. The British genera would arrange 
themselves as follows, and where the value of any of the groups 
was not previously settled, I have added a few explanatory words. 
Ist Subfam. AsaAPHIN-. 
Pleurz bent down at the ends, each with a distinct trigonal facet 
at the anterior edge. 
These are the most perfectly organized Trilobites; they have 
a compact ovate form, and from the deflexion of the margin are 
of considerable depth ; they all, I believe, have the power of roll- 
ing into a ball, and are the only Trilobites having the triangular 
facets at the anterior edges of the ends of the pleura. The fol- 
lowing are British genera and subgenera :— 
Gen. 1. Puacops (in a wider sense than Emmerich). Lateral ce- 
phalic angles prolonged backwards ; glabella wider in front 
than at base ; sides with three large segmental furrows ; eyes 
