Answer:
The cantus of the fourth species has a duration of a whole note with two half notes in the counterpoint. A half note tied over a bar line creates a rhythmic embellishment.
Step-by-step explanation:
Fourth species counterpoint is a compositional technique in Western classical music where a sustained melody, known as the "cantus firmus", is paired with a counterpoint that introduces varied rhythmic patterns.
Typically, the "cantus firmus" is a sustained whole note against which two half notes are written in the counterpoint, with the second note of each pair being tied forward. This creates rhythmic embellishment in the form of syncopation.