134 



G. P. MATTHEW : ILLUSTEATIONS OF 



Ptijclwpnria, Liostracus and Solenopleura, as well as Anomomre aud Conocephali/es, and o-reat 

 confusion has, consequently, arisen in the nomenclature of the Cambrian trilobites ; and 

 this is the more evident when we observe that in some cases the generic name, Conocori/phe, 

 has been used for species of the above subfamily. One can easily see how great a need 

 there is of delinite generic characters in connection with these names, for beside the many 

 species in Scandinavia, Wales, Bohemia, China and other countries, described under some 

 one or more of the above genera, Mr. C. D. "Walcott enumerates no less than sixty species 

 of Ptychoparia in the American Upper Cambrian, and fourteen in the Middle Cambrian, 

 besides a considerable number from all parts of the American Cambrian rocks belonging 

 to related genera. Many of the species which, by French and American writers are 

 included in Plychoparia, or in Crepicephahis and Conocephulites, would, by Scandinavian and 

 and German authors, be placed in the genera Liostracus, Solenoplemu, Anomocare and Euloma. 

 The latter authors make use of Liostracus largely, for such species as the other class of 

 savants would place under Ptychoparia ; but this use of Angelin's genus is obtained by 

 filling up the ellipses left by that author in the definition of the species, and changing it 

 in others, so that, practically, it takes the place of Ptychoparia. I hope, however, to be able 

 to show, in the sequel, that included in Angelin's genus there is a generic type distinct 

 from Ptychoparia. w^hich should bear the name which Angelin originally gave, aud that 

 the other species which have been included here, should be distributed among other genera. 

 In accordance with this view of the proper generic reference of such species of this 

 subfamily, as are found in Div. (Stage) 1 of the St. John group, the following table has 

 been prepared. 



LIOSTRACUS, Angelin. 



In dealing with this genus of Angelin, it appears to the author that the proper method 

 of treatment it is to limit rather than to extend its scope. Angelin's countrymen have 



