BY R. ETHERIDGE, JUNR., AND JOHN MITCHP:LL. 493 



Phacops latigenalis, sp.nov. 

 (PI. xxxix., figs. 3-6; PI. xl., figs. 2-6 and 9.) • 



Sp. Char. — Body. — Oblong ovate. Head-shield or cephalon. — 

 Subsemicircular, but a little wider than twice the length. Glabella, 

 including neck ring, wider than long, the proportion being about as 

 4-3, highly tumid in large specimens, expanded transversely, 

 slightly overhanging in front, and separated from the rudimentary 

 limb by a fairly distinct groove which communicates with the axial 

 furrows, strongly granulate, granules subconical, and nearly 

 uniform in size, sometimes coalescing and forming ridges or 

 wrinkles; glabella grooves very distinct, deep, and in large speci- 

 mens the first and second pair are overhung by frontal and second 

 lobes very decidedly, intercalary groove wide; second pair gently 

 curved or falcate, and in mature decorticated specimens seem to 

 communicate with the axial furrows; first pair widely Y-shaped, 

 the inner branch being subfalcate, passing into the axial furrows 

 at the front angles of the glabella; frontal lobes very large, 

 occupying more than two-thirds of the glabella; second i^air small, 

 subdeltiform; third pair small and suboblong; intercalary ring 

 nodular; axial grooves deep; neck furrow very deep and con- 

 tinuing with equal distinctness across the side lobes to the inner 

 edges of the borders of the free cheeks and thence faintly to the 

 front of the eye, where it is interrupted by the lobe on which the 

 eye rests; neck ring intensely arched, rather narrow, ends nodular; 

 fixed cheeks small; genal lobes deltiform, arched, granular; 

 palpebral lobes lunate, separated from genal lobes by shallow 

 but distinct furrows, which continue posteriorly round and under 

 the eyes, adding to the prominency of those organs; anteriorly they 

 pass into the axial grooves; free cheeks practically smooth, 

 coalesced, extended towards the genal angles, border wide, thick, 

 genal angles flattened, forming large triangular facets on which 

 the first pleur?e imbricate. Eyes half as long as greatest length of 

 cheeks, slightly overhanging, subsemicardioid or lunate; perpen- 

 dicular height small compared with that of most species of the 



