24 PPP, KKroKT OF iMioGravss. james hall. 



liaviiiii" I'onipleted his work, and being no longer connected 

 Avitli the Survey, the specimens have been placed in the 

 hands of the writer for study and illustration. 



The specimens of sliale containing these remains amount 

 to more than twenty in number, some of them containing 

 only fragments of the fossil crustaceans, and nearly all of 

 them containing coal plants. Two of the fossils are very 

 large and fine specimens, being nearly complete. Several 

 other smaller specimens are essentially complete in their 

 parts and well-preserved, though from extreme compression 

 in the black shale it is difficult to see the details of the organs 

 and the surface sculpture. Several of the fragmentary i)or- 

 tions and separated organs of the fossils are very interest- 

 esting and instructive. 



A critical examination shows what are apparently two 

 very distinct forms, which can be clearly characterized, be- 

 sides other portions of much larger forms, which are at 

 present unknown in their entire condition. All the better 

 preserved specimens, as well as all the separated members 

 or fragmentary portions having any important significance, 

 have been drawn in a very complete and artistic manner by 

 Mr. George B. Simpson, and are reproduced in heliotype. 



Although several species of this family have been de- 

 scribed from the carboniferous rocks of Europe, we have 

 heretofore known but a single species from rocks of the 

 same age in America. In the American Journal of Science^ 

 VoL 46, p. 21, 1868, Messrs. Meek and Worthen published 

 the description of Eurypterus {Anthraconectes) Mazo- 

 nensis from the coal measures of Grundy county, Illinois, 

 and the same is illustrated and farther described in the 

 third volume of the reports of the Geological Survey of Illi- 

 nois, page H44, 1868. The accompan\dng illustration, with 

 the explanations, is copied from the volume cited : 



