DESCRIPTIVE REMARKS, xly 
lopod tribe), Beyrichia and Primitia, are very numerous. Beyrichia 
Kledeni, fig. 9, is the most abundant Upper Silurian species, its range 
being from the Llandovery to the Passage beds of the Upper Ludlow ; 
one other species of Beyrichia only is catalogued, B. seligua ; whilst 
Primitia includes nine Wenlock species. 
FossIts oF THE Luptow Rocks. 
The Lower Ludlow Rocks of the Silurian region of England and 
Wales, as Sir R. Murchison states, must be looked upon merely as 
a continuation of the argillaceous beds of the underlying Wenlock for- 
mation : these strata consist of dark-grey shales with small calcareous 
concretions. ‘The central portion of the Ludlow rocks at several places, 
particularly at Aymestry, is an argillaceous dark-grey limestone (called 
the Aymestry Limestone) : over this are more sandy and somewhat cal- 
careous beds, forming for the most part an imperfect thin bedded grey 
earthy building stone, termed the Upper Ludlow Rock, the highest stra- 
tum being occasionally composed of light-coloured sandy freestones and 
tilestones, called Passage Beds, through which the formation graduates 
lithologically and conformably into the lowest beds of the Old Red Sand- 
stone or Devonian rocks ; this being the general order near the town of 
Ludlow, which stands upon the higher strata of the formation. In 
following the formation from the Ludlow tract on its strike or direction 
to the north-west, its included limestone thins out and disappears. 
Lower Ludlow Rocks.—In these shales the single form of Graptolite 
G. priodon, before alluled to as commencing in Caradoc strata of the 
Lower Silurians, figured on Pl. xix., fig. 1, is a very abundant fossil. 
At Leintwardine, Shropshire, where the ascending strata become 
somewhat more sandy, large Orthoceratites, many Crustacea, and Star- 
fishes have been discovered. 
The StarrisHEs belong to genera, and probably to families, distinct 
from any living forms. Paléasterina primeva, Pl. xxiv., fig. 2, isa West- 
moreland fossil somewhat resembling the recent Palmipes roseus. Pa- 
leocoma Marstoni, fig. 8, may be compared with the living genus Pter- 
aster. Protaster Miltont, fig. 4, has the general form of the Ophiure or 
Brittle stars : the two last mentioned are Leintwardine fossils. As many 
as ten species of Starfishes have already been found at this locality ; and 
Professor Wyville Thomson has described two species of Echinoderms 
from the same place, under the name of Echinocystites, which he con- 
siders to be allied to Spheeronites of the Lower Silurians, and Palechi- 
nus of the Carboniferous, although possessing intermediate characters. 
Many Brachiopod shells have been obtained from this stratum which 
are also common to the Wenlock series, such as Pentamerus galeatus, 
Pl. xx., fig. 5; Strophomena depressa, fig. 9 ; and S. euglypha, fig. 8; 
Co 
Do 
