Anguidae

Anguidae View in CoL View at ENA ( Fig. 24R–T View Figure 24 )

In European anguids, the anterior end of the vomer is square in dorsal view and it is wider than the rounded posterior one. The notch of the vomeronasal fenestra is shallow. Posteriorly to it, the lateral margin is convex, whereas the medial one is straight in dorsal view. The convexity of the lateral margin is more marked in Anguis gr. An. fragilis ( Fig. 24R View Figure 24 ) than in Pseudopus apodus ( Fig. 24T View Figure 24 ). Anteriorly, a groove-like structure contacting the vomerine process of the premaxilla is present on the anterior margin. A small osseous expansion is also present on the dorsal surface of the bone, near the anterior end ( Fig. 24R, T View Figure 24 ), marking another, anterolaterally directed groove. Like in gekkotans and scincids, there is a wide posterodorsally directed process on the lateral side of the posterior end, marking the deep articulation surface for the vomerine process of the palatine with a ridge-like ventral margin. In anguids, this process is shifted medially, like in scincids, and presents a well-developed notch at its posterior end. The strongly concave dorsal surface of the vomer is crossed near the middle by a complex of ridges and grooves. In Anguis gr. An. fragilis , a well-developed ridge extends from the lateral surface of the concavity, almost reaching another low ridge developed from the medial one ( Fig. 24R View Figure 24 ); these ridges are separated by a groove and a second groove is visible dorsomedially to the medial ridge, running anterolaterally. A foramen pierces the bone by the base of the lateral ridge, sometimes continuing posteriorly in a groove. In Pseudopus apodus , the medial ridge is absent, leaving only a well-developed and posterodorsally concave lateral one ( Fig. 24T View Figure 24 ). A flattened surface visible in medial view on the anterior-half of the bone is the contact surface with the other vomer. The ventral surface is smooth, except for a low longitudinal ridge in the middle. Some vomerine teeth can be present on the ventral surface of the posterior portion in Pseudopus apodus (see: Klembara et al., 2017).

SEPTOMAXILLA

The septomaxilla ( Fig. 25 View Figure 25 ) is a small, laminar and paired bone, whose morphology varies in the different groups.