448 Dr. H. Woodward—Synopsis of the Species of 
Meek and Worthen have applied this generic appellation to a 
Carboniferous Trilobite from America, there cannot, I think, be any 
very great objection to its use here. 
The pygidium is certainly new, and agrees better with that of 
Proeius (e.g. P. latifrons) than with any other genus with which 
I am acquainted. 
IJ.—Puriurrsta, Porrnock, 1843.—General form oval; glabella 
with nearly parallel sides, marked by either two or three short 
lateral furrows; the posterior angles, forming the basal lobes, 
always separated by a circular furrow from the rest of the glabella ; 
eyes large, reniform, surface delicately faceted ;1 cervical furrow 
deep; free cheek separated from the glabella by the axal suture which 
forms an acute angle with the circular border of the cheek in front 
of the glabella; whilst the facial suture cuts obliquely across the 
posterior margin, just behind the eye, leaving a small pointed portion ~ 
fixed to the glabella by the neck-lobe ; angles of cheeks more or less 
produced, margin of head incurved, forming a striated and punctated 
rim. ‘Thoracic segments nine in number, the axis distinctly marked 
from the side-lobes or pleurze by the axal furrows; the tail, or 
pygidium, usually with a rounded border, the axis composed of from 
12 to 18 coalesced segments. sus 
Puiturps1a Dersrensis, Martin, sp., 1809. Plate XI. Fig. 1. 
Entomolithus (Oniscites) Derbiensis, Martin. 1809. Petrif. Derb. t. xlv. figs. 1 and 2. 
Asaphus raniceps, Phillips. 1836. Geol. Yorks, vol. ii. t. xxii. figs. 14 and 15. 
Phiilipsia Derbiensis, De Koninck. 1842. Anim. Foss. t. lili. fig. 2. 
——— Jonesii, var. seminifera, Portlock. 1848. Rep. Geol. Londonderry, etc. 
Ps 30S, bee ose. 
Derbiensis, Morris. 1854. Cat. Brit. Foss. p. 114. 
Jonesit, var. seminifera, M‘Coy. 1855. Brit. Pal. Foss. p. 183. 
Derbiensis, Salter and Woodw. 1865. Cat. and Chart. Foss. Crust. p. 
16, fig. 11d: 
H. Woodw. 1877. Cat. Brit. Foss. Crust. p. 55. 
H. Woodw. 1883. Pal. Soc. Mon. Carb. Trilob. Part i. p. 
12, pl. i. figs. 1-9. 
Glabella smooth, somewhat gibbous in front; sides nearly straight, 
with two short furrows near the front of the eye, and a circular 
furrow around the basal lobe at each posterior angle of the glabella ; 
neck furrow deep, neck lobe rather broad, with one small tubercle 
on centre; fixed cheek very small; facial suture oblique, leaving . 
a small angular portion attached to the neck lobe on either side. 
Eyes very large in proportion to head; reniform, smooth, but when 
well preserved showing a fine and minutely-faceted surface. Facial 
suture uniting with outer border of free cheek, and forming a very 
1 Messrs. Meek and Worthen, in their description of two Carboniferous Trilobites 
from Illinois and Indiana, remark, ‘‘ eyes apparently smooth, but showing, when the 
outer crust is removed, numerous very minute lenses beneath,’’ Geol. Surv. Illinois, 
vol. v., ‘‘ Paleontology,’’ 1873, 4to. pp. 528, 529. This observation may serve to 
explain the fact that many specimens do not show the faceted surface at all clearly ; 
this is especially the case in the genus Griffithides. Emmrich believed it possible to 
use this character of the external surface of the eyes of Trilobites, as a means of 
classification, but I have not been able to accept his proposed arrangement based on 
this structure. (See Emmrich, De Trilobitis ; Berlin, 8yo. 1839.) 
