Chap. IX.] 
FOSSILS OF THE LLANDOVERY ROCKS. 
211 
very rare , but the small Crania implicata, PI. XX. f. 4, is found occasionally in 
the higher beds. 
The above-mentioned Brachiopod Shells are by no means equally distributed 
throughout the various localities where the Llandovery strata crop out. In the 
Abberley, Malvern, and Tortworth districts, Atrypa hemisphserica, Sow., is the 
common fossil, and Pentameri are rare. At May Hill, and round the flanks of 
the Longmynd, on the other hand, the various species of Pentamerus and 
Stricklandinia prevail, and are accompanied by Orthis calligramma, Dalm., and 
0. reversa, Salt., Strophomena compressa, Sow., Spirifer plicatellus, and Sp. 
elevatus, and, rarely, at May Hill by Chonetes lata, von Buch. The Malvern 
district is rich in a variety of fossils. Besides the Pentameri, Rhynchonella 
decemplicata, Sow., Meristella ? furcata, Sow., and several other species of the 
genus not yet named, we there meet with many fine Lingulse, which have been 
above noticed. In the Abberley Hills Atrypa hemisphserica is the common fossil. 
The small outlier at Presteign (p. 107) contains few species ; but these attain 
a large size, and Pentamerus oblongus and Atrypa hemisphaerica are profusely 
distributed in it. Along the South- Welsh frontier the upper and lower divi- 
sions are marked by their peculiar Pentameri, as already noted, p. 88. 
In the cliffs of Marloes Bay, Pembrokeshire, where the Llandovery rocks 
assume a peculiar mineral structure (see p. 143), the ordinary Brachiopods still 
prevail. Thus Stricklandinia lirata lies at the base of the Wenlock series, with 
a thin layer of Pentamerus oblongus underneath. These are in that locality the 
only representatives of those genera. Rhynchonella decemplicata and a new 
species with two raised ribs in front, Strophomena compressa, and Atrypa hemi- 
sphserica are, however, common. In Galway Orthis calligramma forms entire 
beds ; and the only Pentamerus yet found there is P. oblongus. Atrypa hemi- 
sphserica is also there both numerous and of great size ; and Orthis reversa, with 
Rhynchonella serrata, are common. These species also abound in Ayrshire, 
where Rh. serrata and small forms of Atrypa hemisphserica lie in the upper beds, 
and a large variety of the latter species, with Meristella angustifrons and Orthis 
reversa, in the lower. The distribution in Ayrshire is, therefore, like that in 
South Wales ; and the other groups of fossils, as well as the Brachiopoda, follow 
the same rule. 
Lamellibranchiate Shells are not common ; but certain species are character- 
istic of the formation. A long variety of the Pterinea retroflexa, PI. XXIII. f. 17, 
is plentiful at Malvern, and also in the Connemara tract of Galway, where two 
or three other Ludlow-rock forms occur, such as Pt. sublsevis, M'Coy, and Pt. 
bullata, M'Coy, with Pt. lineatula, Sow., PI. XXIII. f. 16. A small species, 
perhaps inaccurately referred to the genus, Pt. planulata, Conrad, Foss. 60, f. 6, 
is not uncommon in the upper beds of the formation ; it is a Wenlock species. 
Cucullella? ovata and C. antiqua, Sow., are found in Galway. 
Two or three rather large species of Ctenodonta occur near Malvern, such as 
the Ct. lingualis, Phillips, Ct. rhomboidea of the same author, and its variety Ct. 
deltoidea, Phill. There, too, the remarkable thick species, Ctenodonta Eastnori 
and Ct. subsequalis, PI. X. f. 7-9, abound ; Ct. ovalis, PI. XXIII. f. 10, and Ct. 
subcylindrica, M'Coy, are Galway species. Lyrodesma (Actinqdonta) cuneata, 
Phillips, is characteristic of the Upper Llandovery beds in Pembrokeshire. 
A few Mytiloid shells are to be noticed. These are : — Mytilus mytilimeris, 
Foss. 61. f. 6, at Llandovery and May Hill ; two or three species of Modio- 
lopsis at Tortworth ; and the small Anodontopsis bulla, f. 5, a species which 
lived on to the close of the Ludlow rocks, and was first described by M'Coy 
p2 " 
