Précisions sur l'ammonite Rehmannia (Loczyceras) richeï (Flamand, 1911) du Jurassique moyen d'Algérie (Saïda, Algérie nord occidentale)

The ammonite specimens collected in 1976 from the Saïda Clay Formation described in this article are considered as topotypes of the species Rehmannia (Loczyceras) richei (Flamand, 1911), while the nomenclatural status of specimen 6a and 6b, pl. 8 in Flamand (1911) remains stabilized as lectotype. The biozonation established in Algeria by Elmi (1971) is modified. In the Coronatum Zone, Baylei becomes a Subzone and the Villanyensis Subzone takes the place of Horizon. For this species, the statistical tool is applied to measurements of growth parameters taken on the shell [diameter (D), umbilicus (O), height (H) and thickness (E) of the turn]. The results of measurements taken on specimens harvested in the Oued Rhoua and Oued Mansour sectors are plotted on a multiple regression line obtained using STATISTICA software, the graph clearly showing homogeneity in the development and growth of the species. This species belongs to the Rehmannia genus, which is characteristic of the sub-Mediterranean province of the Tethyan domain and thus enables biochronological correlations to be established.