ClipArt ETC
"Five stages in the development of the trilobite Sao hirsuta. A, Youngest stage. B, Older stage with distinct pygidial carapace. C, Stage with two free mesosomatic somites between the prosomatic and telsonic carapaces. D, Stage with seven free intermediate somites. E, Stage with twelve free somites; the telsonic carapace has not increased in size. a, Lateral eye. g, So-called facial "suture" (not really a suture). p, Telsonic carapace." — The Encyclopedia Britannica, 1910

Sao Hirsuto

"Five stages in the development of the trilobite Sao hirsuta. A, Youngest stage. B, Older stage with…