| In all these the genal cca fade out in the genal angles, and in none of them would compound eyes be expected in that region. |
| The relation of the genal cca to the ocelli on the cheeks is best shown in the Trinucleid. |
| Eye-lines occur on trilobites with both simple and compound eyes, and genal cca may or may not be present in both cases. |
| The first genal spine, or first tooth in the head-comb, is shorter in the dog-fleas of both sexes than it is in the cat-fleas. |
| The genal spine of the very smallest specimens is about as long as the remainder of the cheek, and remains distinct until late in meraspid ontogeny. |
| The latter are occasionally continued beyond the ocular tubercle back to the genal angle. |
