Page:The Habitat of the Eurypterida.djvu/28

 Coal Measures in Beaver County, Pennsylvania. Eurypterus stylus of Hall from the Venango beds is probably the same as E. (Anthraconectes) mansfieldi, both type specimens being compressed longitudinally, but otherwise appearing the same. Eurypterus (Anthraconectes) pennsylvanicus C. E. Hall described from a single small carapace from Pithole City, Venango County, Pennsylvania is probably allied to E. mansfieldi, according to Clarke and Ruedemann (39, 428). A few fragments called by Hall E. ? potens also occur in Pennsylvania. The Carbonic eurypterids are in productive coal beds associated with plants and land animals. The fauna and flora at Mazon Creek have been especially studied by Meek and Worthen (170) from whose report the following associates of Eurypterus mazonensis are taken:
 * A Xiphosuran Euproöps danae M. and W.
 * An isopod Acanthotelson stimpsoni M. and W.
 * also A. eveni M. and W.
 * Decapoda: Palaeocaris typus M. and W.
 * Anthrapalaemon gracilis M. and W.
 * Myriopoda: Euphoberia armigera M. and W.
 * Arachnida: Pulmonia: Eoscorpius carbonarius M. and W.
 * Mazonia woodiana M. and W.
 * Architarbus rotundatus Scudder
 * Cock-roach: Mylacris anthracophila Scudder
 * Other insects: Miamia danae Scudder
 * Chrestotes lapidae Scudder

The remains from the Coal Measures of Nebraska were found by Barbour in an outcrop one mile south of Peru in the bluffs facing the Missouri River (10). The formations exposed there consist of alternating shale and limestone changing rapidly to a shale which finally merges into a massive sandstone. In this last bed there occurred a shaly band composed of thin, irregularly shaly layers, seldom half an inch thick, alternating with micaceous sand. This whole band was scarcely a foot thick and extended for over three hundred feet. Even within the band it was only the topmost two inches of the shale seams which yielded eurypterid remains. These were found in considerable abundance, forty specimens so far having been obtained in an area of as many square feet. The chitinous shells, probably representing merely the shed exoskeletons, have in all cases been reduced to carbonaceous films, but except where these are very thin they are in a good condition of preservation so that the grosser anatomy and surface markings can be seen and even some of the minute sculpturing.