[1] The craters La Caille to the southwest and Faye to the northeast border on the outer rim of Delaunay.

This ridge grows increasingly slender as it approaches the southwest rim, until it terminates at sharp point, giving it the appearance of a curved fang.

The outer rim of this crater is equally irregular, and the uneven inner wall varies significantly in width.

The southern rim has been heavily damaged by impacts, including La Caille E which intrudes into the interior.

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Delaunay.