Pre-Dynastic Fishtail Blades

Predynastic Fishtail knives,
Left: MMA 10.176.96, Flint, Naqada I, ca. 39003650 B.C.E.
Center: MMA 10.130.1222, Flint, Naqada II, ca. 36503300 B.C.E.
Right: MMA 24.2.13, Obsidian, Naqada III-Dynasty 1, ca. 33002900 B.C.E.

Round piece is disk-shaped macehead, of hornblende diorite, # 10.130.1207
Flint Fishtail Blades
Naqada I to Naqada II (3900 - 3330 BCE) Obsidian Fishtail Blade
Naqada III- Dynasty 1 (3300 - 2900 BCE)
Photo of info card,
Also see link to museum view of second blade,# 07.228.162, its edge is serrated.
The museum also has a photo of the fourth blade # 10.130.1222

Original photo...

"Fishtail blades are distinctive flint shapes found principally in burials throughout the Predynastic Period. Although the blade's upper portion is skillfully edged with tiny saw-like teeth, the V-shaped edge is the cutting surface. Currently, scholars believe that these blades are an early form of the adze-like implement used in the Opening-of-the-Mouth ceremony, part of the funeral ritual in Pharaonic times. The fishtail blade's exact function in the Predynastic Period is unknown, but as many are found in excellent condition, a ceremonial use is suspected."

The Metropolitan has a miniature Opening of the Mouth tool set, whereby we can see the similarity of the fishtail with the peshkent knife.