﻿100 BRITISH FOSSIL TRIGONI^E. 



the Cretaceous rocks represented by two species in the Devonshire Grecnsand and Upper 

 Greensands and Chloritic Marls of the South Devon coast. Two other European forms 

 are also recorded. The Cretaceous rocks of India have yielded to the researches of 

 Forbes and of Stoliczka four characteristic examples of the section. It is chiefly in the 

 Cretaceous examples of the G/adra, both European and Asiatic, that we discover affinities 

 with the Liassic T. Lwffonensis, species placed almost at the opposite stratigraphical limits 

 of the Mesozoic formations ; these affinities, however, have only a general or sectional 

 resemblance, and refer chiefly to the characters of the area, so little separated from the 

 pallial portion of the surface. 



§ V. Quadrate. 



In Britain the Quadrat ce are represented by four species only, two of these each 

 constitute two varieties ; they possess the several features special to the section 

 prominently developed. Externally their escutcheons have small nodose varices ; 

 internally the posteal portion of the pallial border has a short row of quadrate pits and 

 elevations; there is also a smaller oblique series of pits or furrows at the posteal 

 extremity of the hinge-border. Plate XXIV, fig. 1 a, exemplifies the pallial pits of 

 T. nodosa. T. dcedalea and T. spectabilis have less than half the number of these pits 

 upon their inner surfaces. 



Trigonia DiEDALEA, Park. Plate XXIT, figs. 7, 8 ; Plate XXIII, figs. 2, 3. Var. 



confusa, Plate XXIII, fig. 1. 



Trigonia d^dalea, Parkinson. Org. Rem., vol. iii, pi. xii, fig. C, 1811. 



— ? KUDis, lb. Ibid., fig. 10. 



— D.'EDALEA, Sowerby. Min. Concb., vol. i, tab. hxxviii, 1815. 



— QUADRATA, lb. Geol. Trans., 2nd series, vol. iv, pi. xvii, fig. 10 



(young example), 1836. 



— D^DALEA, Pusch. Polens, Pal^ont., p. 60, 1837. 



— — Agassi:. Trigonies, p. 52, 1840. 



— PALMATA, Beshayes. Leymerie, Mem. Sue. Geol. Fran^., vol. v, pi. viii, fig. 5 



(variety), 1842. 



— QUADRATA, Morris. Catalogue, p. 229, 1854. 



— D^DALEA, lb. Ibid., p. 228 (pars). Exclude Lower Greensand. 



Exclude the Trigonia dcedalea of the following authorities : 



De la Beche, Geological Manual, p. 287, 1832. 



Mantell, Geology of the South-east of England, Appendix, p. 388, 1833. 



