V. UNDÜLAT.C

1. Trigonia sulcaiana Lam. (Tab. Il, fig. 17). T. testa ovato-trigona; costis numerosis, grarilibus, undulatis, pênes margi ne m posticam valde refleelis; area cardinal! lata, ad apiccm leviter plicata; apicc proinincntc. — Creta inferior. {Grès vert).

2. Trigonia undulala Fromb. (Tab. 10, fig. 14-16 et Tab. 6, fig. 1). T. testa subtrigona, antice rotundata, postice obliqua; costis crassis ad margincm poslicam inflectis; area cardiitali bu leviter rugosa; carina marginal! tubcrcuUs crassis pnedita ; apicibus proxiinis. — Jurassus inferior ( Oolile inférieure).