| The floor is prolonged into an infundibulum which contains a prolongation of the third ventricle. |
| The chitinous cuticle that covers the infundibulum extends into and covers the inner surface of the acetabulum. |
| The cuticle is shed from the infundibulum and the acetabulum simultaneously as a single unit. |
| Contraction of the circumferential muscle bundles constricts the infundibulum to a conical shape. |
| A staghorn calculus is a stone that fills the renal pelvis and extends into the infundibulum and calyces, causing dilation of the calyces. |
| The musculature of the wall of the infundibulum is similar to that of the acetabulum. |
