250 CATALOGUE OF THE FOSSILS OF THE PERMIAN SYSTEM 
3. A. INFLATA, Brown. 
Avicula inflata, Brown, Manch. Geol. Tr. 1., pl. 6, f. 25, 26. 
Gervillia tumida, King, Geol. of Russ. i., p. 2251 
In Magnesian-limestone ; not rare. Tunstall-hill. 
This is a more tumid species than either of the former. The 
beaks are small and far apart, so much so that the dorsal margin 
has a wide flattened area, in which are slight indications of mar- 
ginal pits. The surface is striated as in the former species. 
We have several fragments which appear to belong to other spe- 
cies of Avicula, but they are too imperfect to be satisfactorily 
determined. 
Famity. Pzctenipaz, Broderip. 
26. PECTEN, Linnaeus. 
1. P. pusrtuius, Schloth. 
Pleuronectes pusillus, Schl., Mun. Ak., vi., pl. 6, f. 6. 
Pecten pusillus, Miinst., Goldf., Petrif., pl. 98, f. 8. 
In Magnesian-limestone; common. Humbleton, Tunstall, 
Dalton-le-dale. 
This little shell is very regular and convex in shape, having 
the ears nearly equal and the surface quite smooth. In one or 
two localities it is very abundant.. 
Two or three other species of Pecten are mentioned in the 
Geological Transactions, 2nd ser., vol. iii., as occuring at Hum- 
bleton, but after assiduously searching this locality we have not 
been able to discover a trace of them. It is probable that the 
young of I. gryphcoides has been mistaken for other species. 
Orper. PALLIOBRANCHIATA, Slainville. 
Famity. Lineups, Gray. 
27. LINGULA, Bruguire. 
1. L. mytiLorpEs, Sow. ? 
Lingula mytiloides, Sow. Min. Conch. tab. 19, f. 1, 2? 
In Marl-slate; not uncommon. Ferryhill, Thickley. 
Valves of a Lingula are found in the Marl-slate in several lo- 
calities, but it is doubtful whether they belong to the above spe- 
cies to which they have been for some time referred. The 
