Crustacea. | LOWER PALAZOZOIC ARTICULATA. 161 
the pleurze, each side with a small tubercle; plewrw gently arched backwards towards their falciform 
extremity, each with a strong submesial furrow reaching nearly to the end; pygidium as long as the 
head but much narrower, semielliptical, abruptly narrowed towards the apex to form a short flattened 
solid mucronate point, an extension of the lateral margin; awis narrow, of twelve segments, with a faint 
tubercle at each end, lateral ribs eight, separated by deep furrows, and each divided by a fine medial 
sulcus. Average length of pygidium one inch, width thirteen lines. 
At Underbarrow, and Benson Knot, Kendal, occurs a trilobite about one-third the ordinary size of this, 
and of which I have not seen the tail, but which seems. identical in the characters of the head and body 
so far as I have seen, except, perhaps, the lateral cephalic spines may be smaller; it was figured in a 
cancelled plate of this work by Mr Salter as the P. Downingie, from which however it differs in its more 
elongate glabella, more equal side-lobes, and coarsely granulated surface (the latter character being over- 
looked, apparently, by Mr Salter, and not represented in the figure he made of the species). It may for 
the present be called Odontochile caudata, var. minor. 
Position and Locality—Very common in the Wenlock limestone of Dudley ; Llandeilo, Caermarthen- 
shire; Leintwardine; Llanfair Road, W. of Welshpool; above grits Park Lane. 
ODONTOCHILE LONGICAUDATA (Murch. Sp.) 
Ref. and Syn—Asaphus longicaudatus Murch. Sil. Syst. t. 14. f. 11 —13. 
Sp. Ch.—Cephalic shield semioval, external defined margin very large, abruptly extended in front into 
a small, obtuse, tongue-shaped process, extending backwards into very long spines at the lateral angles ; 
glabella clavate, moderately gibbous; pygidium triangular, sides slightly convex, apex running out into a 
slender spine as long as the rest of the pygidium, axis narrow, of fourteen or fifteen segments, eight or 
nine oblique, strongly defined, lateral ribs, each divided by a fine mesial sulcus. Average length of head 
nine lines, width one inch nine lines. 
Position and Locality—Wenlock shale, Chiney Longville, Shropshire; Middleton Park, Llandeilo. 
ODONTOCHILE OBTUSI-CAUDATA (Salt. Sp.) Pl. 1. G. fig. 15, 16. 
Ref. and Syn.—Dalmannia obtusi-caudata (Salt. in Ap.) 
Sp. Ch.—Cephalic shield more than twice as wide as long, slightly angulated in front ; glabella convex, 
clavate, front portion transversely oval, segmental furrows very strong, reaching nearly across, first pair 
inclining obliquely inwards and backwards, second pair slightly forwards, third pair horizontal; first lobe 
equal in size to the second and third together; neck-fwrrow and segment strong and large; cheeks depressed, 
lateral angles with a very small spine. eyes small, close to the glabella, little exceeding the first lobe in 
size, deeply lunate: pygidiwm semielliptical, about twice as wide as long (varies from mechanical causes 
affecting the matrix), margin narrow, angulated at the apex, but not extended into a point; axis very 
convex, gradually tapering, about two-thirds the width of the lateral lobes, having twelve rounded segments, 
lateral lobes flattened, with twelve flattened ribs, each divided by a very fine impressed line. Average 
length of head ten lines, of pygidium six lines. 
In Mr Salter’s engraving of this species the neck-furrow is represented as interrupted in the middle, 
like the lateral segmental furrows of the glabella, but in the specimens it is seen to go right across, as 
in the other Trilobites. 
This species is allied to the P. (O.) caudata, but the margin does not become widened into a flat, 
triangular point, as in that species; the specimens are much distorted. 
Position and Locality—Very abundant in the calcareous flags over the Coniston limestone of 
Coldwell, Westmoreland. 
Explanation of Figures.—P\. 1. G. fig. 15. Cephalic shield natural size.—Fig. 16. Pygidium natural 
size. 
Y, 
