WOODWARD : ON A CARBONIFEROUS TRILOBITE. 
85 
The neck-lobe is prominent, and from the evidence of a 
detached head, we know that there was a central spine or tubercle 
on its axis. 
The axis of each of the nine free thoracic segments (only- 
eight of which can be seen on one (the left) side, owing to an 
overlap) is fringed by very minute tubercles, as is also each 
of the fourteen coalesced somites forming the pygidium. This 
deUcate fringe of minute tubercles also extends along the pleura 
on either side of the axis. The 
margin of the pygidium is rounded 
and has a smooth slightly raised 
border. 
Measurements. — Total length 
of specimen, 17 mm.; greatest 
breadth (across cheek-spines), 
10 mm.; length of head, 6 mm.; 
breadth, 9 mm.; length of nine 
free thoracic segments, 5 mm.; 
breadth, 8 J mm. ; pygidium, 
length, 6 mm.; breadth, 8 mm. 
Affinities. — The two species 
of Griffithides which approach 
most nearly to Mr. Hawkes- 
worth's specimen are Griffithides 
acanthiceps H. W., from the Car- 
boniferous Limestone of Craco, 
Grassington, Yorkshire (see H. 
Woodw., Mon. Brit. Carb. Trilo- 
bites, 1883-4, p. 32, PI. VI., 
Figs. 2, 10, 11, and PI. VII., 
Figs. 2 and 3. Pal. Soc. Vol. for 
1883), and Griffithides Barkei (H. Woodw., Geol. Mag., 1902, 
pp. 484-486, PI. XX., Figs. 14, 15), from the Culm Measures, 
Bishopston, Glamorganshire. 
The former of these differs greatly in point of size, and 
its ornamentation is dissimilar, the head being minutely tuber- 
culated, and the glabella less narrow behind than that of the 
Nidderdale Trilobite. It certainly agrees closely with G. Barkei 
Griffithides barkei H. Woodw. 
Base of the Lower Culm, 
Angram, in Nidderdale, Yorkshire. 
X f nat. 
Drawn by Miss G. M. AVoodward. 
