The ornamental design for a venetian blind, as shown and described.
1. Venetian blind
1.1 is a top back left perspective view of a venetian blind showing our new design;
1.2 is a bottom back right perspective view thereof;
1.3 is a front view thereof;
1.4 is a back view thereof;
1.5 is a top view thereof;
1.6 is a bottom view thereof;
1.7 is a right side view thereof;
1.8 is a left side view thereof;
1.9 is an enlarged detail view of area 1.9 shown in 1.1;
1.10 is an enlarged detail view of area 1.10 shown in 1.2;
1.11 is an enlarged detail view of area 1.11 shown in 1.4;
1.12 is an enlarged detail view of area 1.12 shown in 1.7; and
1.13 is an enlarged detail view of area 1.13 shown in 1.8.
The dash-dash broken lines shown in the drawings illustrate environmental subject matter and form no part of the claimed design. The dash-dot-dash broken lines shown in the drawings illustrate the boundaries of the claim and form no part thereof. The dash-dot-dot-dash broken lines shown in the drawings illustrate the section upon which enlarged detail views are taken and form no part of the claimed design.