50 BRITISH SILURIAN BRACHIOPODA. 
Elton, Evenhay.” But it is only flat from pressure, for well-preserved specimens are 
gently convex, and the front edge is not truncated, but rather rounded, as Sowerby’s 
original figure clearly shows. 
Position and Locality. n the typical localities near the town of Ludlow, it is found 
in Lower Ludlow rocks, occurring at Vinnal Hill, at Elton, and Church Hill, near Ludlow ; 
also in a bed close to the “bone-bed” at Ludford Lane, Ludlow. Also in Lower 
Ludlow at Ledbury and Aymestry, as well as in the Aymestry limestone of Mocktree, 
near Leintwardine, Shropshire; also at Kendal, Westmoreland, &c. In Scotland, in the 
Ludlow beds of the Pentland Hills, where it was first discovered by Mr. D. J. Brown, of 
Edinburgh. 
I am very much puzzled to distinguish specimens found in the Lower Silurian rocks, 
and known by the name of JZ. brevis, Portlock, from Z. data, Sow., for they differ but 
little in size and shape, as may be seen from the series of figures in Pl. III, where 
both species are illustrated. I can scarcely believe that Z. /ata lived also in the 
Llandovery and Caradoc periods, although, to my mind, such would not be an. impossi- 
bility ; however, since many palzontologists might differ from me upon this subject, I 
will provisionally retain Z. drevis as a separate species: and I am quite certain that the 
shell described and figured as Z./ata by Portlock from Tyrone, Desertcreat, in Ireland, 
does not belong to the species described by Sowerby under that designation. 
(?) Lineuxa Brevis, Portlock. PI. ILI, figs. 34—39. 
LinGuLA BREVIS, Portlock. Report on the Geology of the County of Londonderry 
and of part of Tyrone and Fermanagh, p. 443, pl. xxxu, fig. 2, 
1843. 
Spec. Char. Shell small, ovate or oval; sides gently curved; beak acuminate ; front 
rounded ; valves very slightly convex, and marked by fine lines of growth. 
Length 4, width 3 lines. 
Oés. This so-termed species has given me no little trouble, for it was not, at first, 
possible to find Portlock’s figured type; and several examples labelled Z. drevis in the 
Museum of the Geological Survey of Ireland differed slightly from Portlock’s figure, but 
still, I think, not sufficiently so to admit of another designation. 
Portlock describes his Z. drevis as follows :—‘“<Acuminated retrally, but quickly attain- 
ing the full breadth ; sides sub-parallel ; front flat, rounded; length to breadth 5 to 4; 
surface flattened, smooth, and very faintly marked by lines of growth. This has a short 
wide aspect; but it may be the young of another species, the breadth not increasing [in 
this genus] in the same proportion as the length. Three specimens, all small, -19” long. 
Loc. Tyrone, Desertcreat: Sheet 37, No. 2.” 
