Fig. 1. Branching pattern of fin nerve in Sepia officinalis. (A) Drawing illustrating the bilateral branching pattern from a 17.5 cm mantle length male. Primary anterior branches are colored red on the upper half of the diagram and are labeled from anterior to posterior on the lower half of the diagram (A1-A4, bold; colored orange, yellow, green, blue). Primary posterior branches are labeled from posterior to anterior on the upper half of the diagram (P1-P4, bold; colored purple). Subsequent branches (2°, 3°, 4°) are indicated by normal, italic and underlined text, respectively. (B) Photomicrograph showing the branching pattern on the left side of a 10.8 cm mantle length male. Several anterior branches (a), posterior branches (p), and blood vessels (bv) are labeled. Inset is a drawing of the nerves in the photograph; blood vessels are colored black. Scale bar, 2 mm.