ON THE NATURE OF EDESTUS AND RELATED GENERA, 

 WITH DESCRIPTIONS OF ONE NEW GENUS AND 

 THREE NEW SPECIES. 



By Oliver P. Hay, 

 Of Washington, District of Columbia. 



1. DESCRIPTIONS OF THREE NEW SPECIES OF EDESTUS 



EDESTUS CRENULATUS, new species. 



The type and only known specimen of this species belongs to the 

 U. S. National Museum (Cat. No. 6050), and was found in a col- 

 lection of fossils purchased from Mr. G. Hambach, of St. Louis, 

 Missouri. No record regarding the origin of the fossil accompanied 

 it, but there can be no doubt that the specimen had been obtained 

 from the Coal Measures not far from St. Louis, probably from some 

 of the coal mines of western Illinois. No species of the genus is 

 mentioned in Mr. Hambach 's Preliminary Catalogue of the Fossils 

 Occurring in Missouri.'' 



The specimen (pi. 12, fig. 1) is almost as complete as it was on 

 the death of the animal, only the apices of some of the teeth and 

 some of the denticles being broken off and missing. The species 

 resembles most that known as Edestus heinrichU,^ but numerous dif- 

 ferences may be observed. 



The total length of the fossil is 207 mm.; the greatest height is 

 58 mm. ; but to the latter measurement should be added about 2 mm. 

 for the missing apex of the second tooth, counting from the right. 

 The height of the shaft alone is 46 mm., the greatest thickness, be- 

 neath the first tooth, 28 mm. As will be seen from fig. 1, pi. 12, the 



« Geological Survey Missouri, Bull. No. 1, 1890, pp. 60-85. 



* Doctor Eastman (Bull. Mus. Comp. Zool., vol. 39, 1902, p. 05) points out that 

 Nevpberry's specific name heinrichsii was improperly formed. Inasmuch as 

 Newberry expressly says that the species was named for Mr. Heinrich. we may 

 assume that the foi'm heinrichsii was a lapsus calami, and on that ground 

 adopt the form heinrHchii. Newberry himself used this form in 1879 (Geo- 

 logical Survey Indiana, p. 347), although later he used the original spelling. 



Proceedings U. S. National Museum, Vol. 37— No. 1699. 



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