104 INVERTEBRATA. 



The principal muscular impression is of moderate size, situated 

 near the anterior side of the shell at about the middle of its length. 



This species is distinguished from 0. Germanii (Coquand), 

 and 0. Leymerii by the inequality and dissimilarity of its valves 

 and by its ligament area. 0. Leymerii usually has radiating ribs 

 on its lower valve. 



One specimen in the Woodwardian Museum which I refer to 

 this species is indistinguishable from 0. deltoidea (Sow.), and is 

 also very similar to some specimens of 0. Germanii (Coquand), see 

 Pictet and Campiche, St Croix, pi. 189, f. 2. 



Measurements. Length, 1 inches; breadth, 1-| inches; depth, 

 | inch; length of ligament area, finch; breadth of ligament area, 

 ^ inch. 



Locality. Upware. 



N. Europe. Brunswick, Speeton Thon (Coll. Herr von 

 Strombeck). 



OSTREA (GRYPHEA) VESICULOSA, Sowerby. 



Gryphea vesiculosa, Sby., 1823. Min. Con., pi. 369. 



Ostrea vesiculosa, 1869. Coquand, Monog. des Huitres, p. 152, 



pi. 59, f. 47. 

 Pictet and Campiche, St Croix, p. 311, pi. 194, 



f. 1-6. 



An upper cretaceous species, but ranging from our Wicken beds 

 (Neocomian) to the Gault and Lower chalk. 



Localities. Brickhill. I. of Wight ; Warminster, Upper Green- 

 sand. 

 8. Europe. St Croix, Switzerland (Gault). 



PECTEN RAULINIANUS, d'Orbigny. 



Pecten Eaulinianus, d'Orb., 1846. Pal. Fr., Terr. Crtt. III., 



p. 595, pi. 433, f. 69. 



Pictet and Campiche, Pal. Suisse, Foss. de 



St Croix, p. 202, pi. 172, f. 57. 



The cross imbrications are well developed in the Upware speci- 

 mens, traversing the interradial spaces. In some specimens the ribs 



