GEOLOGICAL SOCIETY OF DUBLIN, 
163 
-=1-09. 
n 
Locality: Loughshinny, county of Dublin. 
Fig. 2. P. Becheri, with broad, deep annulations ; showing both valves ; 
cut off abruptly by one of the joint surfaces which are common 
in the distorted shale of Loughshinny, Bush, county of Dublin, 
where these fossils are found in abundance in the black shale 
beds between beds of crinoid and spirifer limestones. 
Locality : Loughshinny, county of Dublin. 
Fig. 3. Typical specimen of P. Becheri from Corry, Drumkeeran, county 
of Leitrim, where it is found in blue shale, resembling the dark 
mud beds of Eush and Kinsale— 
— = 1 * 40 . 
n 
Locality : Corry, Drumkeeran, county of Leitrim. 
P. Becheri .— Testa obliqua elliptica, nix concamerata ; costis multis , 
bene figuratis, culminatis , concentricis ; urnbone parvulo vix eminente, in 
medio cardinis recti posito. 
Professor Bronn considers Posidonia to belong to the Aviculacese, 
and to be intimately allied to Inoceramus. He unites with P. Becheri 
both P. lateralis and P. tuberculata , figured in Sedgwick’s Account of the 
Geology of Devonshire.—Trans. Geol. Soc. London, second series, vol. v. 
Plate LII. 
In this union of species I fully concur, and think it would be highly 
interesting to know whether the specimens figured by Sedgwick were 
found in cleaved beds or not. 
The generic character is thus given by Bronn:— 
Posidonia :—Shell equivalved, unequal; oblique oval, or roundish; 
very thin; both externally and internally concentrically wrinkled; the 
hinge-line straight, long, forming an angle with the rim of the shell, 
both before and behind the scarcely prominent beaks. 
PLATE XIX. 
Figs. 1, 2, 3.—Specimens of P. Becheri, variously distorted by cleavage. 
Fig. 1. 
- = 1*96, 
n 
= 42°. 
Fig. 2. 
- = 2*58, 
n 
<j> = 53°. 
Fig. 3. 
— = 2‘11, 
n 
<)> = 22°. 
Locality': Old Head of Kinsale, county of Cork. 
