xlvi DESCRIPTIVE REMARKS. 
Atrypa reticularis, fig. 4; and Rhynchonella Wilsont, Pl. xxiv., fig. 8. 
Lingula lata, Pl. xxv., fig. 1, is perhaps the only Brachiopod peculiar 
to this division of the Upper Silurians. 
Of the Concurrera, Cardiola interrupta (before alluded to), Pl. 
xxv., fig. 5, is the most common; this species has also been found in 
the Caradoc, not yet in Llandovery strata ; characteristic in the Wenlock 
shale, and more particularly so in the present division of the Ludlow 
rocks. Another bivalve, doubtfully referred to the same genus,|?] Car- 
diola striata, fig. 6, is equally characteristic, and up to the present time 
only known in Upper Silurian rocks, occurring in all the fossiliferous 
localities of Shropshire and the neighbouring regions. 
Amongst the CrpHatopopa the largest and probably the most com- 
mon is Orthoceras Ludense, of which a much reduced figure is shown 
on Pl. xxvi., fig. 8, and O. filosum, Sil., Pl., xxvii., fig. 1. The only 
common species of Lituites is LZ. giganteus, Pl. xxvi., fig. 7 (reduced 
to half natural size). Phragmoceras pyriforme, fig. 6, is a remarkable 
pear-shaped shell having the mouth or opening contracted into a key- 
hole form. 
A large species of the singular crustacean Pterygotus has been found 
in these rocks at Leintwardine, and described by the late Mr. Salter as 
P. punctatus; Mr. Henry Woodward has since referred this form to 
Eurypterus.* 
Fish remains of the genus Péeraspis has also been discovered in this 
Lower Ludlow locality, being the first evidence of Vertebrata, which had 
been hitherto only known from Upper Ludlow strata. 
Aymestry or Luptow Limesrone.—This central portion of the Lud- 
low formation was named by Sir R. Murchison after the village of 
Aymestry. The Aymestry limestone is principally developed in Here- 
fordshire and Shropshire, and again at Sedgeley, in Staffordshire. It 
is a dark-grey limestone passing into a highly calcareous flagstone, and 
may generally be recognised by its well-defined joints and predomi- 
nant fossils ; in some parts of South Wales, where the calcareous matter 
is absent, it is difficult to trace even the place of this band in the Lud- 
low rocks. 
The large Brachiopod, Pentamerus Knightit, Pl. xxv., fig. 2,f is one 
of the predominant fossils of the Aymestry limestone, together with 
Lingula Lewisit (Pl. xxiv. fig. 5); Rhynchonella Wilsont, fig. 8; Stro- 
phomena euglypha, Pl. xx., fig. 8; Atrypa reticularis, fig. 4; Belle- 
rophon dilatatus, Pl. xxii., fig. 1, and many other Corals, Shells, and 
Trilobites common to the Wenlock limestone. 
Urrrr Luptow Rocxs.—This series of strata is the most diversified 
* “ Quart. Jour. Geol. Soc.,” 1868, vol. xxiv., p. 290. 
+ The name applied to the genus of shells to which this species belongs relates to its 
capability of division into five parts, in consequence of its possessing thin septe—two at- 
tached to the ventral, and one to the dorsal valve. The facility with which the shell 
separates on applying a chisel, and giving it a smart tap where one of these lines are visible, 
defining the longitudinal septa, is remarkable, asa section is disclosed through both valves 
similar to that shown by fig. 2c, on the. same Plate. 
