50 PROCEEDINGS OE THE GEOLOGICAL SOCIETY. [Dec. 4, 



end long, and narrowing gradually towards the extremity, which is 

 also rounded. A moderately strong ridge strikes off from the umbo 

 towards the posterior margin, but diminishes in strength gradually 

 as it approaches it. Beak depressed. Hinge-line long and straight. 

 Surface rounded and faintly marked with lines of growth, pallia! 

 margin gently curved. 



Differs from M. ramseyensis, which it most nearly approaches, in 

 being much narrower, less convex, and in having the posterior ex- 

 tremity evenly rounded. 



Loc. Eamsey Island and Tremanhire. 



Modiolopsis solvensis, spec. nov. PI. V. figs. 18 & 19. 



Bhomboid oval, less than half an inch long by about -^ wide. 

 Anterior extremity short ; posterior long. A very strong ridge ex- 

 tends from umbo to posterior margin, and another nearly equally 

 strong to anterior margin. Posterior edge rounded ; anterior angular. 

 Hinge-line long and straight. Shell nearly equally wide, excepting 

 near its posterior extremity, and strongly raised along the line of the 

 ridges. Muscular scars large and distinct. This species differs from 

 the others in its rhomboidai shape and angular ridges. 



Loc. Eamsey Island, Tremanhire near Solva, and St. David's. 



Modiolopsis cambriensis, spec. nov. PI. V. fig. 20. 



Nearly oval, | of an inch long, and about | wide. Both ex- 

 tremities almost equally rounded. Beak nearer anterior margin, 

 tolerably well raised and pointed, surface ridged from beak to pos- 

 terior margin. Shell compressed. Lines of growth perceptible 

 near margin. More oval in shape, and hinge-line shorter than in 

 the other species. 



Loc. Eamsey Island. 



Beilerophon solvensis, spec. nov. PI. ILL fig. 33. 



A small species, of three very gradually increasing whorls, about 

 §• of an inch in diameter. Surface smooth, sides inflated. Only 

 one specimen has been found ; but this is sufficient to show thai 

 the species is new and distinct from any hitherto found in rocks 

 of this age. 



Loc. Tremanhire near Solva, and St. David's. 



Bellerophon ramseyensis, spec. nov. PI. III. figs. 30-32. 



Broad, involute, with the outer whorl greatly expanded, and ridged 

 on the back ; | of an inch in diameter. Surface smooth. 

 Loc. Eamsey Island and St. David's. 



Theca Davidii, spec. nov. PI. III. figs. 28 & 29. 



Elongated and compressed. Two inches and a quarter long, and 

 a fourth of an inch wide at the mouth. Surface marked with strong 

 transverse lines, very slightly arched. 



Loc. Eamsey Island and St. David's. 



