THE SHELL -LIMESTONE OF DURHAM. 167 



were found by Professor W. King, at Tullyconnel, near Artrea, 

 county Tyrone, Ireland, and were forwarded by him to me for 

 examination ; and sketches of them, with my remarks, were pub- 

 lished in Professor King's paper on Irish Permian Fossils in the 

 "Journal of the Geological Society of Dublin," vol. vii., 1856. 



The specimens indicate a somewhat almond-shaped carapace, 

 nearly straight on the ventral, and obliquely arched on the 

 opposite border, tapering somewhat anteriorly, and fuller and 

 rounder behind. In shape it apj^roaches C. inornata^ M'Coy 

 (a Carboniferous species, to which some Permian individuals have 

 been referred, see p. 170), but it is proportionably narrower, and 

 of much greater size. Specific differences are difficult to be 

 satisfactorily recognised in the very similarly shaped carapaces 

 of Cytheres of this type, especially in the fossil state; nevertheless, 

 for the sake of registering this Irish Permian form, I propose to 

 term it Cythere Tyronica. 



4. C. RiCHTERIANA, SpCC. UOV. PI. XI., figS. 21« 21c. 



The specimen here figured (from the Zechstein of Koenitz) 

 was placed in my hands some years ago by Professor King, and 

 I take this opportunity of describing it. 



Carapace bean-shaped, convex, compressed anteriorly, flat- 

 tened above and below, smooth, punctate; rounded at the 

 ends; anterior rather narrower than the posterior ex- 

 tremity, and less symmetrically outlined; back faintly 

 arched ; ventral border gently sinuate. Valves margined, 

 except along the hinge-line, with a very narrow flattened 

 rim, strongest round the ends. In profile the carapace 

 is acutely ovate or lanceolate; in cross section, sub-quad- 

 rate. 

 This is a well marked species; and I dedicate it with much 

 pleasure to my obliging friend Dr. Richter, of Saalfeld, who has 

 added considerably to our knowledge of pala30zoic fossils. 



5. C. AMPUTATA, Kirkhy. PI. XI., figs. 22a — 22d. 



This species is described in full by Mr. Kirkby, at p. 155. 

 The figures here given do not essentially differ from those given 



