ILLtENUS. 



207 



The general sculpture of the surface is coarse, and is arranged thus : on the head 

 it lies transversely, and is very strong along the front margin ; in old specimens (fig. 2) it 

 appears quite squamous there. For half the length of the head it follows the direction of 

 the front margin (woodcut, fig. 53), and is then met rather abruptly, above the level of the 

 eye, by the more direct and fainter lines of the middle portion, and here the hues inosculate. 

 Behind, the head shows somewhat finer hues, and a central tubercle some way up (see fig. 

 la). Among the coarse striae are abundant puncta, wide and strong, the marks, probably, 

 of the bases of short pile or stiff hairs. Similar lines, mixed with puncta, run trans- 

 versely across the whole thorax, parallel to the course of the rings ; both, however, vanish 

 about the fulcral points. The puncta are not closely placed on the caudal shield. 



British Localities. — May Hill Sandstone, Malverns (M. P. G.) ; Purple shales, Onny 

 River, Shropshire (Mr. Wyatt-Edgell's Cabinet). Woolhope ? Grits of Bogmine, Shelve, 

 Shropshire, rare (M. P. G.). Woolhope Limestone of Woolhope, Herefordshire (abun- 

 dant) ; Hay Head, Barr, Staffordshire ; Malvern Tunnel (abundant) ; Wenlock Shale of 

 Rushall Canal, near Wallsall (the late Mr. Mushen's Coll.). Wenlock Rocks of Llandeilo ; 

 Llandovery; Carmarthen ; &c., as far as Freshwater, Pembrokeshire (M. P. G.). 



Foreign. — Niagara Limestone, New York, Wisconsin, &c. 



Ill^nus (BuMASTUs) iNSiGNis, Hall. {11. pomatia, on plate) PI. XXVH, figs. 6, 7. 



Ill^nus Bakeiensis (in part), Murchison. Sil. Syst., p. 656, pi. vii bis, fig. 3 ; pi. xiv, 

 fig. 7, 1839. 



— — Hall. Geol. Rep., New York, p. 102, No. 10, fig. 4 ; No. 



IP, fig. 3? 1843. 



— — Salter. Decades Geol. Survey, No. 2 (pi. iii, fig. 2 ; pi. iv, 



figs. 9—1 1 only) ; Siluria, 2ud ed., pi. xvii, fig. 9—11. 1859. 

 II. INSIGNIS, Ball. 18th Report on the New York State Cabinet for 1865 (printed in 

 advance, Dec. 1864). 



//. modicus, 3-4 uncialis, capite paraholico, caudd hemispharicd. Caput gihhomm 

 antice ovatum, margine refiexo ; sulcis axalihus pnimum convergentibus, dein longe divari- 

 catis et in foveas angustas desinentibus. Oculi humiles dejlecui, pulvillo nullo fulti. Anguli 

 obtusi. Cauda subhemispharica, tam longa quaiu lata fere, margine acuto. Superficies, 

 caput pracipue, lineis creberrimis. 



As above noted, this fine species has all along been confounded with the //. Barriensis, 

 from which it differs in every particular. More convex, with obhquely placed eyes, 

 which have no fold beneath them — deep pits [fovea) at the end of the axal furrows in 

 front of the eyes — a close hneation of the surface ; and above all, a highly convex tail- 

 piece, which is subhemispherical and nearly as long as broad, — these are characters which 

 distinguish the species, at a glance, from the much more common II. Barriensis. 



It is not nearly so large a fossil as the last, probably never more than 4 inches, but 



