PHACOPS. 57 



Localities. — Var. a, Woolhope Limestone, Presteign ; Wenlock Shale of Cheney 

 Longville and Burlington, Shropshire (abundant) j Usk, Monmouthshire ; also Carmarthen- 

 shire, Brecon ; and Maiioes Bay, Pembrokeshire, more rarely. It is quoted also from 

 Wenlock Limestone, Malvern, in the Survey lists. 



Var. /3, Grindrodianus. PI. Ill, figs. 2 — 28. 



Head, including the short front mucro, somewhat more than half as long as wide. 

 Glabella, at its widest, not more than one third the width of the head. Forehead-lobe 

 prominent. Tubercles on head, body, and tail, conspicuous. Tail with few (5 — 6), side- 

 furrows, and about ten axal rings ; the spine not more than equal to the rest of the tail. 



This variety, of which we fortunately can examine a fine suite of specimens, differs 

 from the typical form in points which do not affect the specific characters given above. 

 It is only less extravagantly armed, — the front, rear, and side-spines being all shorter. The 

 side-spines reach to the seventh segment. The surface shows the tubercles characteristic 

 of the young, — in the adult state ; both on the forehead-lobes and the lower lobes of the 

 glabella, on the axis of the body, 1 and on the fourth and eighth segment of the axis of the 

 tail. The gland-like tubercles on the fourth side-pleurse are not always conspicuous. 



The mucro is shorter, seldom equalling the tail itself in length. The side-ribs are 

 five, strongly duplicate to the very end, and the margin very narrow. 



Locality. — Var. Z 3 , Wenlock Shale. It is known only at Malvern Tunnel and Dudley. 



Phacops Weaveri, Salter. PI. Ill, figs. 1—3 j PL IV, figs. 6—9. 



Phacops Weaveri, Salter. Decades Geol. Surv., ii, art. 1, p. 7, pi. i, fig. 16. 

 — — Id. Morris's Catal., 2nd, ed., p. 114, 1854. 



P. Icevis, capite quam in P. caud. nisi trigono lobisque glabella tumidioribus. Cauda 

 triangularis, fere cequilatera, multicostafa, convexa, apice acuto brevimucronato ; awi 13 — 16- 

 annulato, costis later alibus 10 — 12 simplicibus, vix curvis, ad marginem angustum abrupte 

 terminatis. 



We know but little vet of this fossil. It is fragmen- v , - 



tary as yet; and though I believe the specimens here figured 

 all belong to one species, I would prefer to keep the name 

 for the fossil of the May Hill Sandstone. 



The head is very imperfect j what there is of it strongly 

 resembles P. caudatus, except that the lobes are a little 

 more tumid ; the forehead-lobe is more strongly marked 



Head of P. Weaveri ? Canada. 2 



1 It seems that when the tubercles exist on the sides of the axis, they are not present towards the 

 centre, and vice versd. But it is not every segment which has the tubercles at all. 



2 I have good reason to believe this Canadian species, brought by Sir W. Logan from He Perce, 



8 



