The upper (suprarostral) and lower (infrarostral) supportive jaw cartilages have pigmented and keratinized jaw sheaths. The relative amount of dark keratinization (width in longitudinal dimension) of a sheath sometimes is useful for distinguishing among tadpoles.
Narrow Sheaths-dark for less than half the width
Medium Sheaths-dark for about half the width
Wide Sheaths-dark for nearly the entire width
Other jaw sheath characteristics are sometimes useful to distinguish among species.
Tutorial Index|Morphology|Measurements|Eyes|Lateral Process|Tail Musculature|Spiracle
Vent|Oral Disc Morphology|Labial Tooth Row Formula (LTRF)|Back to the Key