264 Mr. T. Davidson on French Liasic Bpirifers. 



Caen, where many remarkable specimens have been found by 

 M. Deslongchamps, Bouchard, Tesson and others. 



Plate XV. fig. 8. A specimen from Fontaine-etoupe-four, in the coll. of 

 M. Bouchard. Fig. 9. Another from the same locality. 



4. Spirifer oxypterus, Buv. PI. XV. fig. 5, 6, 7. 

 Spirifer oxypterus, Buvignier, 1843, Mem. de la Soc. Philom. de 

 Verdun, tome ii. p. 14. pi. 8. f. 8 ; Geol. des Ardennes, 

 p. 534. pi. 5. f. 5. 



Diagnosis. Shell inequivalve, variable in shape, transverse ; 

 valves convex ; beak more or less produced and recurved ; area 

 short ; deltidium in two pieces ; hinge-line considerably exceed- 

 ing the width of the shell, extending in the shape of wings ; sur- 

 face ornamented by a wide elevated mesial fold in smaller valve 

 and corresponding sinus in larger one, with from four to six 

 rounded lateral costse on each side of the fold and sinus ; struc- 

 ture punctuated and spinose; dimensions variable. Length 11, 

 width 19, depth 8 lines. 



Obs. This remarkable species was first brought to light by 

 M. Buvignier, who discovered it in the Liasic beds of Carignan 

 Sachy (Ardennes), where it is rare, and is easily distinguished 

 from all the other Liasic Spirifers by its wings, reminding us of 

 many Palaeozoic forms in which the hinge-line greatly exceeds 

 the width of the shell. M. Tesson likewise found this species 

 many years ago in the Lias of Fontaine-etoupe-four near Caen, 

 and I was so fortunate as to pick up another specimen at Croi- 

 silles near Caen. 



Plate XV. fig. 5. illustrates the original type obligingly sent me by M. 

 Buvignier ; it is from the Ardennes. Fig. 6. The specimen found 

 by myself at Croisilles. Fig. 7- M. Tesson's specimen from Fon- 

 taine-etoupe-four. 



5. Spirifer Signiensis, Buv. PI. XV. fig. 3. 



Spirifer Signiensis, Buv. 1843, Mem. Soc. Philom. de Verdun, 

 t. ii. p. 14. pi. 5. f. 9 ; Geol. des Ardennes, p. 534. pi. 4. 

 f.9. 



Diagnosis. Shell inequivalve, transversely oval ; valves convex, 

 but depressed, ornamented by a well-defined mesial fold and 

 sinus, nearly twice the width of the lateral plaits, these last vary- 

 ing from eight to nine on each side of the mesial fold and sinus ; 

 beak produced, not much recurved; area narrow, triangular; 

 deltidium in two pieces; hinge-line shorter than the width of 

 the shell. Surface punctuated and spinose ; dimensions variable. 

 Length 8, width 13, depth 14 lines. 



Obs, This interesting species was discovered by M. Buvignier 



