Fig. 10.

Pentecopterus decorahensis, prosomal appendage IV. a SUI 139937, fragmentary appendage showing moveable spines. b SUI 140000, podomeres 2–3 showing development of spines on the ventral distal podomere margin. c SUI 139927, termination of appendage. d SUI 139926, most complete example of appendage known, comprising podomeres 5–8, and lateral portion of carapace with marginal rim. e SUI 140012, podomeres 6–8. f SUI 139928, fourth podomere showing moveable spines. g SUI 139938, podomere displaying ventral distal extension and development of marginal spines. h SUI 139940, podomeres 6–8. i SUI 139959, coxa showing development of ancillary spines surrounding gnathobase. j SUI 139946, coxa and second podomere. IV-5–IV-8 = podomeres 5–8, CP = coxal projection, DS = distal swelling, GB = gnathobases, MR = marginal rim. Scale bars = 10 mm