The mine consists of a long, slender corridor with a narrow central frass line.

The mine has the form of a long slender corridor at the underside of the lower leaves.

The mine consists of a slender corridor, mostly partly following the leaf margin.

The mine consists of a slender corridor that hardly widens.

The first part of the mine is a long, slender corridor, rather straight, often following a vein or the leaf margin.

The mine consists of a full depth, slender corridor.

The mine consists of a long, slowly widening, slender corridor.

They moved inside and traversed a very slender corridor.

The mine consists of a slender corridor, hardly widened in the end.

The mine consists of a slender corridor with a broad frass line.