Of the 246 specimens examined, 200 (81.3%) have both primary temporals in contact with their adjacent postoculars. Thirteen specimens (5.3%) have only the left primary temporal in contact with the postocular and eight (3.3%) have only the right primary temporal in contact with the postocular. Twenty-five specimens (10.2%) have both primary temporals separated from the postoculars. Separation of the primary temporal from the postocular, whenever it occurs, results from contact of mutual extensions from the adjacent parietal and supralabial (usually the fifth).
Nasal
Of the 243 specimens examined, 237 (97.5%) have the nasal divided below the naris on both sides. Three specimens have the nasal completely divided (above and below the naris) on only the left side; one specimen has a completely divided nasal on only the right side. A groove, but not a complete division of the nasal, is present above the left naris of one specimen. One specimen lacks the typical division below the naris on both sides, but a complete suture is present posterior to the naris and the resulting postnasal scales are, according to position, loreals.
Contact of prefrontal with supralabials
Of the 243 specimens examined, 147 (60.5%) have the prefrontal separated from the labials on each side. Of the remaining 96 specimens, 53 (21.8% of the 243) have the prefrontals in contact with the second labial on each side; five other variations of this characteristic were observed ([Table 2]).
Table 2. Variation in Contact of the Prefrontals and the Labials in 243 Specimens of Tantilla gracilis.
| Characteristic | Number of specimens | Per cent of occurrence |
|---|---|---|
| No contact | 147 | 60.5 |
| Contact of prefrontal with second labial on right | 26 | 10.7 |
| Contact of prefrontal with second labial on left | 10 | 4.1 |
| Contact of prefrontal with each second labial | 53 | 21.8 |
| Contact of prefrontals with labial two on left and labial three on right | 1 | 0.4 |
| Contact of prefrontals with labial three on left and labial two on right | 3 | 1.2 |
| Contact of prefrontals with labial two on left and labials two and three on right | 3 | 1.2 |
The specimen having the prefrontal in contact with labial 2 on the left and labial 3 on the right has seven supralabials on the right, the extra labial being added anterior to the eye. In two of the three specimens with the prefrontals in contact with labial 3 on the left and labial 2 on the right, the preoculars and prefrontals are fused on each side; the third specimen has each preocular reduced to a small vertical sliver. Of the three specimens having the prefrontals in contact with labial 2 on the left and labials 2 and 3 on the right, two are typical with respect to other characteristics that might result in this atypical condition, but one has the prefrontals and preoculars fused.