Fauna of the Niagara and Ui^per Silurian Rocks. 117 



that I have never seen a single specimen of llloenus ioxus, found • 

 in Schoonmaker's Quarry, notwithstanding Prof. Hall's mention 

 that it is of frequent occurrence, and Prof. T. C Chamberlaiu 

 identifies it as belonging to this quarry. 



A nearly perfect head and pygidium of an Acidaspis Danai 

 make the specimen quite different from Winchell's Acidaspis Ida. 



Extraordinary sized Ceraurus insignis are occasionally found 

 and well marked parts of Bronleus Acmas, Harpes, Lichas, Dalma- 

 7iia, uew species of lUoenus, Asaplms, besides quite a number of 

 as yet undetermined varieties of trilobites, which are "new or but 

 little known," 



Fine specimens of lUoenus ioxus are found in Waukesha and "^ 

 and Greenfield, but it is in the Eacine quarries that the grand pa- 

 triarchial ioxus assumed his supremacy. Specimens of heads 

 over five inches wide and three inches deep, and joined to thoracic 

 segments, and pygidium will make full-sized specimens, more 

 than one foot in length. The Acidaspis and several other very re- 

 markable varieties of trilobites are also found, beautiful as well as 

 unique, and unsurpassed. But it is in the the Wauwatosa quar- 

 ries that the best documents are produced to illustrate the com- 

 parative anatomy and physiology of the trilobite. A critical ex- 

 amination of fossil specimens of this invertebrate animal reveals 

 a bundle of contradictions on account of its possessing many at- 

 tributes belonging to several orders, which cause the trilobite to 

 assume as uncertain a position among the invertebrates as a Chei- __ 



roptera does among vertebrates " which can claim a habitation ^^ '^ 

 neither with birds or beasts." y^ 



All the parts of the trilobite, as found at Wauwatosa, b^ng 

 "casts of the interior," reveal an internal mechanism which re- 

 quires no more stretch of the imagination to localize and impute cer- 

 tain actions to different parts, than for an anatomist to explain 

 definitely and intelligently the properties and powers pertaining 

 to the skeleton of a vertebrate. 



Precisely in similar manner do the casts of the trilobite illus- 

 trate its organism, habits and locomotion. Like some species of 

 Entromostracans, it was capable of being dismembered into sev- 

 eral parts and had the attributes of Crustaceans, Mollusks and 

 Worms. Its ambulatory movements were performed in a similar 



