| Species are diagnosed on the basis of carinal height and the nature and number of flanking rows or parapets. |
| Ritter recognized the following four morphological groups in a Sweetognathus lineage based on carinal configurations. |
| The bundles contain both xylem and phloem, and are marked by the presence of large canals known as carinal canals, which also function in water conduction. |
| The crests for the carinal depressor muscle are barely developed. |
| The basal margin on the carinal side of the spur is sometimes a little hollowed out. |
| The carinal margin of the valve is just perceptibly bowed, and is formed by rectangularly upturned lines of growth. |
