1853.] MORRIS LINCOLNSHIRE OOLITES. 341 



Tancredia axiniformis, Phil. sp. Pl. XIV. fig. 4a, 4b. 



Syn. Nucula axiniformis, Phil. Geol. Yorksh. i. t. 11. fig. 13. 



Testa ovato-elongata, aut subtrigona, umbonibus medianis acuniinatis, 

 parvis et depressis, latere postico angulo obliquo subacute, margine 

 ligamenti recto obliquo elongato. 



Shell ovately elongated or subtrigonal, rather compressed ; umbones 

 mesial, depressed, but acuminated and small ; posterior side with an 

 oblique angle, which is rather acute, and separates a posterior space 

 which is somewhat concave ; hinge-margin straight, oblique, and 

 elongated ; anterior extremity of the shell pointed ; posterior extre- 

 mity slightly truncated. 



This form is intermediate between T. angulata and T. extensa, 

 Lycett. The external figure is nearly that of the latter shell, but the 

 posterior angle in that species is much less prominent, and the space 

 posterior to it, which is very narrow, is smaller, and has not the con- 

 cavity of T. axiniformis ; the general figure is also somewhat more 

 convex than T. extensa. 



Length 1 1 lines ; height 6 lines. 



Locality. — Ponton, Lincolnshire ; also in the inferior oolite of 

 Yorkshire and great oolite of Gloucestershire. 



Tancredia angulata, Lycett. Pl. XIV. fig. 5, 



Testa ovato-subtrigona, umbonibus medianis acutis, latere antico com- 

 presso, postico angulum obliquum formante, margine cardinal! brevi 

 recto, basi cm-vato. 



Shell ovately subtrigonal ; umbones mesial, acute and prominent ; 

 anterior side compressed, its extremity pointed ; posterior side with 

 an oblique obtuse angle separating a flattened posterior portion ; 

 ligamental margin short and straight, basal margin with a consider- 

 able curvature. 



This species is distinguished from Tancredia curtansata (Corhula, 

 Phil.) by the more acuminated umbones and by the posterior angle ; 

 from the inferior oolite T. donaciformis, by the more prominent acute 

 umbones and more lengthened form ; the posterior aperture is only 

 slightly indicated. 



Height 9 lines; length 14 lines. 



Locality . — Ponton . 



Ne^ra Ibbetsoni, Morris. Pl. XIV. fig. 6. 



Testa subglobosa, pyriformi, subsequivalvi, striata, umbonibus magnis sub- 

 medianis, latere antico rotundo, postico producto brevi bicarinato, basi 

 curvato, lateribus plicis regularibus inconspicuis, nucleo Isevi. 



Shell subglobose, pyriform, subequivalve, striated ; umbones large, 

 rounded, mesial ; anterior side rounded ; posterior side attenuated 

 and produced, and bicarinated, the anterior carina sharp ; lower 

 margin curved ; the sides with regular slightly impressed plications ; 

 nucleus smooth. 



A very convex and nearlv equivalve shell, with an acutely marked 



2 A 2 



