William C. Massey (1966) use a key that was based on judgmentally selected point attributes to classify 1,079 projectile points and knives in the Castaldí collection from central and southern Baja California. He considered up to five attributes in classifying each point: the presence or absence of a stem; the stem's width relative to the base; stem shape; shoulder shape; and base shape. The points were assigned to 33 types:

• I. Without stem
  • B. Leaf-shaped: l. Pointed base (n = 7), 2. Convex base (n = 221), 3. Straight base (n = 37), 4. Concave base (n = 23)
  • C. Triangular: 1. Convex base (n = 29), 2. Straight base (n = 72), 3. Concave base (n = 118)
  • D. Diamond: 1. Pointed base (n = 27), 2. Convex or straight base (n = 14), 3. Concave base (n = 2)
    
    
• II. With stem
  • A. Stem wider than base: 1. Convex base (n = 5), 2. Straight base (n = 12), 3. Concave base (n = 68)
  • B. Stem narrower than base
    • 1. Tapering stem
      • a. Rounded shoulder: 1. Pointed base (n = 38), 2. Rounded base (n = 55)
      • b. Straight shoulder: 1. Pointed base (n = 35), 2. Rounded base (n = 60)
      • c. Barbed shoulder: 1. Pointed base (n = 17), 2. Rounded base (n = 20)
    • 2. Parallel-sided stem
      • a. Rounded shoulder: 1. Convex base (n = 13), 2. Straight base (n = 22)
      • b. Straight shoulder: 1. Convex base (n = 18), 2. Straight base (n = 12)
      • c. Barbed shoulder: 1. Convex base (n = 6), 2. Straight base (n = 11)
    • 3. Expanding stem
      • a. Rounded shoulder: 1. Convex base (n = 17), 2. Straight base (n = 16), 3. Concave base (n = 60)
      • b. Straight shoulder: 1. Convex base (n = 7), 2. Straight base (n = 4), 3. Concave base (n = 21)
      • c. Barbed shoulder: 1. Convex base (n = 5), 2. Concave base (n = 7)
        
        

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  Reference Cited

  Massey, William C. 1966. The Castaldí Collection from Central and Southern Baja California. Contributions of the University of California Archaeological Research Facility No. 2. Berkeley.