208 BRITISH FOSSIL TRIGONIJE. 



approach to the horizontal figure, their tubercles are very irregular and unequal, always 

 much elevated, and sometimes pointed or spinose. All the Lincolnshire specimens are 

 remarkable for the regularity and uniformity of the rows of costae ; each row ends 

 posteriorly with a tubercle, which is one of the largest, affording a marked contrast 

 with the posteal extremities of the costae in the Inferior Oolite species, in which they 

 become attenuated, and curve upwards to the carina at a more considerable angle. An 

 examination of very numerous Tealby specimens proves that the large Norfolk specimen 

 (Plate VIII, fig. 1) represents the ultimate stage of growth, and that the little accessory 

 costae near the pallial border is altogether an exceptional feature, and is not represented 

 in Tealby specimens. 



Trigonia radiata, Ben. Page 73. 



The remarks upon the French example of this species figured by Messrs. De Loriol 

 and Pellat, ' Mon. Paleont. de I'etage Portlandien de Boulogne,' pi. 8, fig. 1, forming 

 the concluding sentences of p. 73, require the following emendation. My friend Dr. 

 Wright, who has compared the original specimen in the possession of M. De Loriol with 

 the figure in the work of that author, informs me that the anteal portion of the specimen 

 retains the test, which is therefore altogether devoid of ornamentation. The only 

 undoubted British specimen known continues to be the one figured by Miss Benett. 



Trigonia producta, Lye. PL XIII, figs. I, 2, 3, 4 ; PL XXXVII, figs. 1, 2, p. 60. 



It having been objected to the figs, of this species on Plate XIII that they do not 

 represent sufficiently the usual aspect of the Cotteswold forms, the two figures on Plate 

 XXXVII are added, as they exhibit the more frequent condition in which the species 

 occftrs, together with the partial effacement of the surface ornaments over the middle 

 portion of the valves. Plate XIII, fig. 3, represents the hinge-processes of the specimen, 

 Plate XXXVII, fig, 1. Plate XIII, fig. 2, represents a specimen in an unusually fine 

 condition of preservation, having the tubercles both of the costae and carinae, more than 

 usually prominent for one of the Undulata, over the whole of the specimen. 



In the Cotteswolds it is a rare Trigonia, and is limited in position to the hard 

 whitish limestone of the Upper Trigonia beds, or to the sandy grits by which it is 

 replaced. In Oxfordshire it has occurred less rarely, and has been collected by the 

 Officers of the Geological Survey in the sandy beds at Hook Norton, associated with 

 Trigonia signata. As a correction to p. 62, line 7, erase Northamptonshire and 

 substitute Oxfordshire. 



