Crustacea. ] LOWER PALAXOZOIC ARTICULATA. 167 
Position and Locality Caradoc sandstone of Mulock, Dalquorhan ; schists of Pwllheli; schists of High 
Haume; limestone of Acton Scott; limestone of Leintwardine ; a small variety at Coed Sion, and Coniston 
Water, seems only to differ in size, giving the following additions :—axis narrow, the segments tubercular 
at their ends; pleuree more than twice as wide as the axis, abruptly bent downwards at about one-third 
their length from the axal lobe in front, but almost directly from their origin nearer the pygidium ; pygi- 
dium nearly vertical, as in the CO. Blumenbachi, the middle lobe with about five segments, five lateral ribs 
separated by large furrows, each divided by a small medial sulcus. 
Explanation of Figwres.—P\. 1. F. fig 9. Imperfect head, natural size, from the limestone of Leintwar- 
dine.—Fig. 9a. Profile of ditto—Fig. 10. Perfect specimen of small variety from Coniston.—Fig. 10 a. 
Profile of ditto magnified, shewing the great width of the side portions both of the head and body. 
CALYMENE PARVIFRONS (Salt. in Ap.) Pl. 1. F. fig. 7. 
Sp. Ch.—Width of the cheeks equal to the length of the cephalic shield; front three-fourths the length 
of the glabella, margin subtruncate, not reflected, tumid in the middle; glabella slightly wider than long, but 
little convex, lateral lobes prolonged very obliquely forwards and outwards, the anterior pair obsolete; neck- 
furrow small; cheeks large, tumid ; antennary punctures large ; eyes very small, their upper edges on a line 
with the upper edge of the glabella. Length of cephalic shield six lines, width one inch four lines. 
The general depression and great size of the margin in front of the glabella, and very forward position 
of the eyes, seem to distinguish this species. 
Is this the Oalymene incerta of Barrande? It is possibly a Pharostoma of Hawle and Corda, but as 
we have only the middle piece of the head, it is not certain. 
Position and Locality—Only one specimen has occurred in the Porphyry Slates of Tahirion, near 
Arennig Fawr, Merionethshire. 
Explanation of Figures—P\. 1. F. fig. 7. Cephalic shield, natural size—Fig. 7 a. Profile of ditto. 
CALYMENE TUBERCULOSA (Salt.) 
Ref—Mem. Geol. Surv. Vol. IT. t. 12. 
Sp. Char.—Cephalic shield minutely granulose, nearly semicircular, depressed, front rounded, a slightly 
reflexed margin-plate, nearly one-half the length of the glabella, in front of its anterior end; glabella as in the 
C. brevicapitata, but only two-thirds the width of the cheeks at base; eyes rather before the second glabellar 
tubercle, near the upper angle of the cheeks, which are moderately convex ; body depressed ; axis convex, narrow, 
the segments with a small rounded tubercle at each end; plewre at least one-third wider than the axis, 
flattened at their axal half, and rapidly curved downwards from thence to the extremities; knee at about 
half their length from the axis in the anterior portion, approaching the axis towards the tail portion behind ; 
the pleural suleus most prominent at the angle; pygidiwm granulose with more convex lobes, and more rounded 
posterior margin than the C. Blumenbachii; axis flattened with seven rounded segments ending in obscure 
tubercles ; five lateral ribs with strong dividing furrows becoming gradually obsolete at the margin. 
The broad margin in front of the short conical glabella, the great width and flatness of the pleuripedes in 
proportion to the axis, and the convexity of the rounded pygidium, separate all the parts of this from the 
C. Blumenbachii. The head closely resembles that of the C. brevicapitata, but is easily distinguished by the 
narrowness of the base of the glabella when compared with the posterior margin of the cheeks. 
Position and Locality —Common in the Lower Ludlow shale of Garden Quarry, Aymestry, Herefordshire ; 
Wenlock, S. Cheney Longville, Shropshire; upper Ludlow rock of High Thorns, Underbarrow. 
Subgenus. HOMALONOTUS (Kénig). 
Syn. = Trimerus + Dipleura. (Green). 
Gen. Char.—Buckler semielliptical, convex in the middle, obtusely pointed in front, lateral angles not pro- 
duced ; glabella indistinct, simple, subquadrate, with concave sides, narrower in front than behind, not reaching 
