DISTRIBUTION AND OCCURRENCE OF EURYPTERIDS 515 



Germany are known. Four species of Eurypterus are found in the Coal 

 Measures of Pennsylvania ; one, represented by fragments, in Nova Scotia, 

 and E. (Anthraconectes) mazonensis in fragmentary condition in the 

 Coal Measures of Mazon Creek, Illinois. Particular attention should be 

 called to the occurrence of Eurypterus mansfieldi, which Hall has fig- 

 ured, 113 showing the specimen just as it was found lying on ferns in a 

 very perfect state of preservation. In fact both the Eurypterus, of which 

 there are many individuals, and the ferns are so well preserved that it is 

 evident that neither animal nor plant could have been transported far, 

 but that both must have been buried in or near the very place where they 

 had lived. There is now little doubt that these Coal Measure beds are 

 non-marine, so that the five Carbonic species of Eurypterids from North 

 America can be added to the non-marine ones of the previous periods. 

 From the Coal Measures of Europe are reported Arthropleura armata 

 Jordan, a fragment in the Saarbriicker Schichten in the middle Upper 

 Carbonic of Germany, and A. mammatus Salter, from fragments at Pen- 

 dleton Colliery near Manchester, England. Jordan has also recorded 

 fragments of Adelophthalmus granosus from the Saarbriick beds. All of 

 these are non-marine. A single species of Eurypterus (Edonvillei de- 

 fima) has keen found in the Eothliegende of Portugal associated with 

 Walchia pinniformis and Splienopliyllum tlierun in a typical non-marine 

 formation. 114 



Review of the evidence. 115 — Eeviewing the distribution of the Euryp- 

 terids as outlined above by Miss O'Connell, we are impressed with the 

 fact that the sediments and their faunas indicate that it is only under 

 peculiar conditions that the Eurypterids are found in abundance and 

 perfection and never under normal marine conditions. Omitting from 

 consideration the merostomes of the Middle Cambric beds described by 

 Walcott, as they are not Eurypterids, we have only the striking occur- 

 rences of these organisms in abundance in association with typically ma- 

 rine forms in the shales of the Hudson series in the Mohawk and Hudson 

 valleys. In the Mohawk Valley the shales have been determined to be 

 the shore equivalent of the Trenton limestones farther west, while the 

 beds furnishing the Eurypterid remains near Catskill in the Hudson 

 Valley are shown by their associated graptolites to be of Normanskill age. 



m Second Geological Survey of Pennsylvania, Report of Progress PPP, pp, 23-85, pis. 

 3-8, especially pi. 4. 



114 Clarke and Ruedemann, loc. cit., p. 112. 



115 By the author, a more elaborate discussion of this subject will appear in Miss 

 O'Connell's paper. Pari of 1km- conclusions are here made use of. the subject having 

 been under repeated discussion between us in the preparation of her memoir during the 

 past two years. 



