150 
Adult individuals of this species are usually longer than broad, while 
young individuals are usually broader than long. In spite of this difference 
this species is not difficult to identify, if care be taken to collect a sufidcient 
number of specimens showing the almost insensible modifications of the shell 
in its various stages of growth. Again, the concentric folds, which ornament 
the surface and sometimes become true ridges of growth, render it impossible 
to confound this species with P. pimctatus, which is the only one to which 
it has some resemblance ; then again it never reaches the size of P. punciatus ; 
and finally, the concentric bands of P. punctatiis are always flat, and covered 
with much more numerous and slender spines and tubercles. 
Dimensions. — The two specimens sent me are only six millimetres long 
by seven broad. 
H.orizon and Localities. — This species is more frequent in the Upper 
Carboniferous beds than elsewhere. It is not uncommon at Vise, nor in 
the neighbourhood of Glasgow. One of the specimens sent me by the Uev. 
W. B. Clarke was found by him in a grey sandstone slightly tinged with 
yellow, near Tilleghary ; and the other in a dark grey limestone on the banks 
of the Kama and Williams E-ivers. 
Productus scabeiculus, Martin. 
Conchyliolithus anomites scahriculus, Martin, 1809, Petrif. Derbieusis, p. 8, pi. 8G, fig. 5. 
Droductus scahriculus, Sowerby, 1814, Min. Conch., p. 157, pi. 69, fig. 1. 
,, ,, Defiance, 1826, Diet. Sci. Nat., XLIII, p. 350. 
,, ,, Pleming, 1828, British Animals, p. 378. 
„ ,, Keferstein, 1834, Naturgesichte des Erdkopers, p. 666. 
,, ,, Deshayes in Lamarck, Animaux sans Vertebres, VI, p. 383. 
,, ,, J. Phillips, 1836, Geol. Yorkshire, II, p. 214, pi. 8, fig. 2 and 20. 
„ quincuncialis, Idem, 1836, ibid., p. 214, pi. 7, fig. 8. 
Leptcena scabricula, Eischer de "Waldheim, 1837, Oryct. Gouv. Moscou, p. 142. 
JProductus scahriculus, Desor, 1840, Traduction de la Conch. Min. de Sowerby, p. 106, 
pi. 51, fig. 1 and 2. 
,, antiquatus. Von Buch, 1841, Abhandl. k. Akad. Wissen. Berlin, I, p. 29 
(non Martin). 
