CO. T. Trechmann—Brachiopods from Durham. 541 
specimen are noticeable. At the extremity of the other spine (b) 
a small Strophalosia has fixed itself by attaching its ventral beak 
and by winding the long, matted spines of its ventral valve around 
the Productus spine. The specimen shows the spines of the ventral 
valve, the area of both valves and the surface of the dorsal valve. 
The latter is nearly flat and is devoid of spines but the concentric 
lamellar growth-lines are well seen, together with the hinge teeth 
of the ventral and a median septum in the dorsal valve. 
It does not closely resemble any of the specimens of Strophalosia 
illustrated by W. King in his Permian Monograph, pl. xii; these, 
however, are, with the exception of one from Whitley, from various 
localities in the Shell Limestone of the Middle Magnesian Limestone 
of Durham. 
INCHES 
Fic. 2.—Sketch of a specimen of Productus horridus Sow., with long spines 
on the ventral valve. c, part of interior of the dorsal valve; a, 
a specimen of Hpithyris elongata Schloth. ; b, a specimen of Strophalosia 
lamellosa Gein. 
Calcareous Lower Magnesian Limestone, East Thickley: Quarry, Durham. 
Neither does it agree with any of T. Davidson’s figures of English 
Permian specimens, illustrated in his monograph of Permian 
Brachiopoda, pl. i1. Turning to Geinitz,) however, one finds a 
species which he calls S. lamellosa, in which the dorsal valve is almost 
circular in outline, nearly flat, and free from spines. I have some 
specimens collected and labelled by the collector, Robert Eisel, of 
Gera, as belonging to this species, which very closely resemble the 
specimen under discussion. They are said to come from zone 3 2 of 
the Lower Zechstein, of Roschitz, Répsen, near Gera, and are in a 
remarkably finely preserved testiferous state, as are the Thickley 
specimens also. The species S. lamellosa is questionably quoted by 
King as a synonym of his S. Morrisiana. Davidson figures several 
specimens all from the English Shell Limestone, and calls them 
S. lamellosa Gein., var. Morrisiana King, and var. Humbletonensis 
King. He discusses the matter further in a supplement to his 
+ Der Dyas, Leipzig, 1861, pl. xviii, figs. 1-7. 
2 These zones appear to be local divisions established in the Gera district. 
So far as I remember from conversation I had with R. Hisel in 1913 the zones 
of the lower Zechstein are characterized by different shape-variants of 
Productus horridus. 
