100 INVERTEBRATA. 



mesial angle of the whorl. From P. Delahayesii, d'Orb., it is 

 distinguished by its taller form, small umbilicus, distinct spiral 

 striations, and mesial sinus-band. P. Favrina, de Loriol, has 

 a characteristic depression around the umbilicus. 

 Locality. Potton. 



LAMELLIBRANCHIATA. 



(See ante, p. 19.) 



Ostrea (Exogyra) Couloni (Defrance), d'Orbigny. 



Gryphea Couloni, Defrance, 1821. Diet. Sci. Nat. xix. p. 534. 

 E. subsinuata, Leym. 1842. Mem. Soc. Geol de France, torn. V. 



pp. 11, 16, 17, PI. 12, figs. 3—7. 

 Ostrea Couloni, 1846. d'Orb., Terr. Cret. pi. 467. 



„ „ 1858. Pictet and Renevier, (pars), Pal. Suisse, 



Terr. Aptien, p. 138. 

 „ „ 1861. de Loriol, Mont Saleve, p. 110. 



MM. Pictet and Renevier have united this species with 0. 

 (Exogyra) sinuata (Sow.), (Foss. du Terr. Aptien, Pal. Suisse, 

 p. 138), and in N. Germany the two names are usually regarded 

 as synonymous. But de Loriol (Foss. du Mont Saleve) doubts 

 the wisdom of that arrangement, and I agree with him that the 

 two forms may well be kept separate though they are closely 

 allied. I find that where Exogyra sinuata (Sow.) occurs there 

 E. Couloni is also found — but the converse does not always 

 obtain — as at Upware, Farringdon and Mont Saleve. 



The true sinuata (Sby.), may be called Ex. Couloni var. sin- 

 uata (Sby.). 



Measurement. Length of largest specimen, 2| inches. 



Localities. Upware, Brickhill, Speeton (Lower Neocomian)^ 

 Tealby, Potton. 

 N". Europe. Brunswick, Hils Thon, and Hils Conglomerat. 

 S. Europe. Perte du Rhone, Mont Saleve. &c. 



