l )s 4 A'. L. Moodii — Mason Greek Shales. 



above mentioned occur at the same level, but not in so great 

 numbers as at the Mazon locality. The shales immediately 

 above the coal frequently yielded magnificent specimens of 

 fossil ferns and other plants." 



The same nodules are thrown out of a coal mine at Braid- 

 wood, Illinois, and doubtless close search would reveal other 

 localities where the shale is cut through in mining. The beds 

 at both localities, along Mazon Creek, are slightly folded. This 

 is especially true of the " upper beds," where a conspicuous 

 fold causes the beds to disappear, to reappear in the bed of 

 the creek a mile and a half north. This is directly across the 

 large " ox-bow'" bend of the creek. Mr. Carr said that he had 

 followed the creek around the bend without discovering any 

 new outcrops of the shales. 



The beds at Mazon Creek -were first explored in 1 S57 by Mr. 

 Joseph Evans, who sent his specimens to Berlin. Germany, 

 where they excited great interest. It was he who collected 

 the type specimen Ampliibamns grandiceps, Cope. Since the 

 time of Mr. Evans many have collected at Mazon Creek, and 

 without doubt the fossil-bearing nodules from the locality are 

 more widely scattered in the museums of the world than are 

 organic remains from any other one bed. The most eager and 

 faithful collector at these beds has been Mr. J. C. Carr. He 

 has presented many collections to schools and individuals, as 

 well as furnishing material for many paleontologists. The 

 writer is indebted to him for the presentation of an excellent 

 series of nodules. The nodules at Mazon Creek will always be 

 abundant, and the collecting will always be good so long as the 

 creek continues to carry away the drainage of the region. We 

 may thus hope to learn much, in the future, of the animals and 

 plants of this wonderful locality. It is not possible, on account 

 of the value of the land, to do extensive excavating, and this is 

 not necessary, for the waters of the creek will, in time, make 

 all the necessary excavations. 



It is quite interesting to note in this place the discovery of a 

 similar bed of fossil-bearing nodules in the banks and bed of 

 Rock Creek near Twin Mounds Post-office, some 22 miles 

 southwest of Lawrence, Kansas. The nodules have been 

 known and collected for some time, and their similarity to 

 those of Mazon Creek has been noted. The nodules at Twin 

 Mounds contain identicalby the same genera and species of 

 plants, insects, spiders, Crustacea, and a Prestwichia ( Eupro- 

 ojy-s) dance, M. & Vi'.. as are found at Mazon Creek. There 

 have been, so far, no evidences of vertebrates ; even fish copro- 

 lites and scales are wanting. Further search max reveal these, 

 as well as an interesting amphibian fauna. The beds at Twin 

 Mounds will be fully described elsewhere, and further mention 

 need not be made of them here. 



