The depression in which the calyx is set is technically called the basin, and several terms are used in describing it.

Abrupt basin. A basin in which the sides show a sudden slope. Corrugated basin. A basin in which the furrows are wrinkled or folded about the calyx lobes. Mammiform basin. A basin in which peculiar fleshy protuberances occur about the base of the calyx lobes.

Obtuse basin. A basin in which the sides show a very gradual slope. Regular basin. A basin in which the sides are smooth. Ridged, ribbed, and furrowed. Terms expressing slightly different degrees of the condition in which depressed lines extend up the sides of the basin.

Fig. 39. A, narrow basin; B, wide basin; C, obtuse basin;.

D, abrupt basin

Symmetrical basin. A basin that is nearly round, or uniform in shape. Wavy basin. A basin in which the furrows are indistinct.