RHYNCHONELLA. 69 



62. Rhynchonella Wrightii, Dav. Plate XIV, fig. 1. 



Diagnosis. Shell inequivalved, spherical, almost as broad as long; larger valve 

 moderately convex ; beak acute, not much produced ; foramen small, almost entirely 

 surrounded by the deltidium, a small portion being completed by the umbo ; imperforated 

 valve very convex, gibbous ; hinge margin slightly indenting the smaller valve ; exterior 

 striated and plaited, the striae which cover all the surface longitudinally are very numerous, 

 minute, and irregular, sometimes bifurcating, nine or ten occupying the width of a line ; 

 the plaits only appear on the anterior half of the valves, eleven or thirteen in number, three 

 of which form a well-defined mesial fold, and two in the sinus of larger valve ; structure 

 unpunctuated ; length 18, breadth 16^, depth 15 lines. 



Obs. This fine species was discovered by Dr. Wright in the inferior Oolite of 

 Leckhampton Hill, along with Ter. simplex and T. plicata; it is quite distinct from 

 B. furcillata and B. rimosa, although belonging to the same small group; it appears to be 

 very rare, and has not yet been noticed on the continent; the specimen figured is from the 

 collection of Dr. Wright. 



63. Rhynchonella furcillata, Theodori, Sp. Plate XIV, figs. 2, 3, 4, 5. 



Terebratula furcillata, Theodori; de Buck, 1834. Uber Terebrateln j et Mem. de la 



Soc. Geol. de France, 1838, vol. iii, 1st series, p. 143, 

 pi. xiv, fig. 13. 



— — Rcemer, 1836 — 38. Dei Versteinerungen des Norddeuschen 



Oolithen-gebirges Tafel. xiii, fig. 2. 



— — C. Rouillier, 184 7. Bull, de la Soc. Imp. de Moscow. 



— — Bronn. Index Pal., 1848, p. 1237. 

 Rhynchonella furcillata, B' ' Orbigny, 1849. Prodrome, vol. i, p. 239. 



Diagnosis. Shell inequivalved, transverse, wider than long ; large valve slightly convex, 

 beak acute, produced, not much recurved ; foramen entirely surrounded by the deltidium, 

 which also presents a slight tubular expansion; false area generally well defined; hinge 

 margin not much indenting the smaller valve; sinus deep. Smaller valve most convex at 

 the umbo, which is also the deepest part of the shell ; the mesial fold is well defined, the 

 sides sloping rapidly downwards. The posterior halves of the valves are ornamented by a 

 variable number of small plaits, from forty to sixty, most of these uniting by two, three, and 

 four, towards the middle of the valves, form large angular costse, which extend to the 

 margin; the number of these last also varies on the mesial fold, which is composed in 

 different specimens of two, three, four, five, six, and seven plaits. Structure unpunctuated. 



Length 10, breadth 12, depth 8 lines. 



Obs. It is stated, that Theodori first named this shell in his collection, which name was 



