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Wisconsin Academy of Sciences, Arts, and Letters. 



manner to the larvae of insects, but its exteiior covering of crusta- 

 ceous segments, united by chitine, enabled it to move rapidly in 

 the water similar to the moUuscan Chiton. It also possessed the 

 same natatory powers as the Crustacean Macrurans. or it could 

 assume a spherical form like an Isopod, or lepidoptera hairy larva. 

 By the action of its extension or flexor muscles, the trilobite was 

 enabled to elongate or contract its size from several inches in 

 length to one-third its longitudinal extension capacity, and did 

 not possess a single attribute of an arachnoid. If a name were 

 required for such an organization, it would be one suggestive of 

 three orders of genera, combined in one, indicative of an annelid, 

 a Mollusk, and a Crustacean. Such a proposition is the result of 

 a careful examination of many thousand specimens of several 

 genera and species of trilobites, and I am induced to believe that 

 this peculiar invertebrate lived, at certain distinct periods of time, 

 so well defined, as to indicate a sufficient reason for making a 

 change in the ages of Geological History. For instead of classi- 

 fying the Silurian age as one of Mollusks, and the Devonian as 

 I one of Fishes, substitute a Trilobite age. For Mollusks existed 

 through all ages, and fishes first appeared in the later part of the 

 Silurian, and assumed a prominence in subsequent ages, like the 

 Devonian, Carboniferous, etcetera, but the Trilobite is identified at 

 the commencement, and became extinct at the close of paleozoic 

 life. In a paper like this, treating- of a miscellaneous fauna, I can 

 only thus give a brief synopsis of the component parts of Trilo- 

 bite, which, like the Crustacea, by aid of muscular action could 

 be "sessile or stalked eyed," and its having a chitine carapace 

 nnited by sutures, was provided with processes, and sinuses for 

 the attachment and action of muscles, and it could be readily dis- 

 membered at its dissolution into cheeks, glabellre, hypostoma, 

 thoracic segments and pygidium, that were held in proper posi- 

 tion by a chitinous bond of union, which enabled the trilobite to 

 perform its wormlike motions by expansion, adhesion and contrac- 

 tions, or to fold its extremities together as the caterpillar larva, or 

 wood louse when alarmed, or if attacked as a means of defense, or 

 could move swiftly through the water, like the Molluscous Chiton 

 or Crustacean crawfish. 

 After many years of patient research and with the aid of 



