THE 
GEOLOGICAL MAGAZINE. 
NEW SERIES. DECADE II. VOL. X. 
No. XI—NOVEMBER, 1883. 
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I.—Synopsis OF THE GENERA AND SPECIES OF CARBONIFEROUS 
LIMESTONE TRILOBITES. 
By Henry Woopwarp, LL.D., F.R.S., F.G.S. 
(PLATE XII.) 
(Continued from p. 464.) 
II.—Grirriruies, Portlock, 1883.—Outline oblong oval; gla- 
bella pyriform, gibbous in front, destitute of lateral furrows; basal 
lobes inflated; cervical lobe broad; eyes small, lunate, smooth ; 
axial furrow clearly defined, outline of free cheek broadly triangular, 
outer posterior angle sometimes produced into a cheek spine. Thorax 
with nine segments; pygidium rounded, composed of from ten to 
thirteen coalesced somites. 
There has been much confusion among writers upon the Carboni- 
ferous Limestone Trilobites, as to the generic characters which may 
be relied upon in separating Phillipsia from Griffithides. While fully 
admitting the difficulty which arises from having so frequently to 
determine the genus and species of these Carboniferous forms upon 
a pygidium alone, yet whenever the head is preserved, we venture 
to think there ought not to be any hesitation. 
The following brief diagnosis of the characters may be found of 
use in separating the two genera most commonly met with :— 
PHILUIPSIA. GRIFFITHIDES. 
1. Sides of glabella nearly parallel. 1. Glabella pyriform. 
2. Marked by either two or three short 2. No short lateral furrows on the 
lateral furrows. glabella. 
3. Basal lobes continuous with the 3. Basal lobes distinct from the glabella. 
glabella. 
4, Eyes large, reniform. 4, Kyes small, suboval. 
GRIFFITHIDES SEMINIFERUS, Phillips, sp. 1836. Pl. XII. 
Fig. 1, and la. 
Asaphus seminiferus, Phillips. 1836. Geol. Yorks, vol. ii. p. 240, pl. xxii. figs. 
8, 9, 10. 
Phillipsia gemmulifera, De Koninck. 1842. Animaux Foss. Terr. Carb. Belgique, 
p- 603, pl. lui. fig. 3 (non Phillips). 
———- M‘Coy. 1844. Synopsis Carb. Foss. Ireland, p. 163. 
seminifera, Morris. 1854. Cat. Brit. Foss. p. 114. 
Salter and H. Woodw. 1865. Cat. and Chart. Foss. Crust. 
p. 15, fig. 110. 
———— ——— H. Woodw. 1877. Cat. Brit. Foss. Crust. p. 55. 
Griffithides seminiferus,H. Woodw. 1883. Pal. Soc. Mon. Carb. Trilob. part i. 
. p.28) pl vetigs: 1-9. 
ee _—— 
DECADE II.—VOL. X.—NO, XI. él 
