Crustacea. ] LOWER PALAZOZOIC ARTICULATA. 151 
The simplicity of the head, there being but one enclosed space on each side of the glabella, and 
the transverse segmental furrow in front of the neck-furrow (which is not indicated clearly by Hawle 
and Corda), separate the genus from the other groups of Lichas, Se. 
ACANTHOPYGE ANGLICA (Bey. Sp.)* 
Ref. and Syn.—Arges Anglicus (Bey. Untersuch. iiber Trilobiten). 
Sp. Ch.—Cephalic shield about four lines long; middle part of the glabella two lines wide, the gibbous 
oval space on each side about one and half lines wide; granulation scattered, of numerous unequal mammi- 
lated tubercles, the spaces between which are minutely granulated. 
This species has been placed by Beyrich in the genus Avges from which the presence of the eye-lid alone 
would separate it; as it seems to agree correctly with Acanthopyge of Hawle and Corda, I have placed it in 
that genus. By the imperfect description I should have supposed the Lichas parva of Barrande allied to 
this, but as Hawle and Corda in redescribing that species, make no mention of Beyrich’s figure, I suppose 
they are distinct. 
Position and Locality.— Wenlock Limestone, Dudley. 
Genus. TROCHURUS (Barr.) 
Syn. = Corydocephalus (Hawle and Corda.) 
Gen. Char.—Cephalathorax semicircular, lateral angles a little prolonged ; gladel/a large, gibbous, middle 
portion narrow, subclavate ; three segmental lobes on each side large, the anterior pair obliquely pyriform, the 
middle pair oblique, oval, the posterior pair much smaller, transversly oval; neck-furrow strong, not wider 
than the base of the glabella; checks triangular ; eyes small; eye-line cutting the lateral margin in front of 
the angles; body of eleven segments, pleurz flat, slightly faleate, and rather wider than the axis, each with 
a fine slightly sigmoid pleural furrow, not reaching the edge; no facets; pygidiwm semicircular, axis narrow, 
three-jointed, two first joints narrow, ring-shaped, third contracted, extending to the margin which is thickened, 
sides flat, each with two narrow straight segmental ridges, extending from the axis beyond the thickened 
margin into thick narrow spines, the middle of the margin at the end of the axis produced into two small 
spines, extending backwards like the rest. 
The number of the body-rings, and form of the pygidium and glabella, separate this genus from Lichas. 
See description of Stawrocephalus below. 
TRocHURUS NoDULOsUS (Salt. Sp.) Pl. 1. F. fig. 16. 
Syn.—Lichas nodulosus (Salt. in Ap.) 
Sp. Ch.—Pygidium semielliptical, aais semicylindrical, reaching little more than half-way to the margin, 
rather less than its anterior half occupied by three narrow ring-like segments, the terminal mass very gibbous, 
and connected with the thickened margin by an abruptly smaller slender prolongation ; lateral lobes, with two 
broad segments on each side, gibbous, most so near the margin, each divided by a wide mesial sulcus, and 
extending beyond the margin in a long slender flattened spine directed backwards; the middle lobe has 
a broad thickened margin; on each side of the small mesial ridge two tumid spaces, separated by a longi- 
tudinal suleus, not crossing the margin ; two thick spines extending backwards, one on each side of the middle : 
surface with fine close granules and small scattered obtuse tubercles. Length, three and half lines, width five 
and half lines. 
Position and Locality—Rare in the schists of Pont y Glyn, Diffwys, near Corwen. 
Explanation of Figure.—P\. 1, F. fig. 16.—Pygidium natural size. 
* As this sheet was going to press I received the Journal of the Geological Society for August 1850, in which Mr 
Fletcher gives figures of this species under the name Lichas Bucklandi (Milne Edw. sp.)—but as M. Edwards’ name was 
merely given to an unintelligible figure, without description of any of the essential parts, there can be little doubt that 
Beyrich’s name is the proper one to use. 
