They arise from the palate, and are attached by flexible membrane to the sides of the mandible.

Those standing towards the middle are the longest, being about one-third of an inch in length, and they project fourteen one- hundredths of an inch beneath the edge.

At their bases there is a short subsidiary row of obliquely transverse lamellae.

In these several respects they resemble the plates of baleen in the mouth of a whale.