L-type ventral organization

A term so named because of the longitudinal nature of the sulcus. The sulcus is more or less straight. The sixth precingular plate (1i) is bounded to left and right by almost parallel sutures and anteriorly by a gabled margin due to its contact with both the fourth and first apical plates or their homologues (A, 1u). The fourth apical plate or its homologue (A) is typically not long and narrow, and does not contact the anterior sulcal plate (ai). There is commonly a broad contact between the last precingular plate and the first apical plate or its homologue (1i/1u). See also S-type ventral organization. Refer to Text-Figure 82.