148 



MEMOIRS OF THE NATIONAL ACADEMY OF SOIENOES. 



measure next overlying it. The shaft from which it was taken, penetrating both, the exact posi- 

 tion of the rock containing it could not be ascertained when we discovered it in the 'dump' or 

 rock pile." Another specimen from Scotch Hill railroad cut, Pittston, Pa. Coal E. Lacoe's No. 6'. 

 8f-34. 



Note on the validity of the Genus Euproops. 



By referring to the synonymy of Prestwichia dance, it will be seen that in 1865 it was referred 

 by Messrs. Meek and Worthen to Belinurus for reasons given in Palfeontology, vol. iii, of the 

 Geological Survey of Illinois, p. 547. After the appearance of Dr. H. Woodward's paper read 

 before the Geological Society of London in 1866* in which the genus Presticichia was separated 

 from Belinurus, the American form was referred to the new genus, Prestwichia, by Mr. Meek. 



"At a later date (February, 1867), Mr Woodward published excellent figures in the Quart. 

 Jour. Geol. Soc, London, vol. xxiii, pi. 1, of the typical forms of both Preswtichia and Belinurus. 

 From these it became evident that the peculiarities of the ridges of the head of the form on which 

 he founded the genus Prestwichia, and which we had supposed probably due to some accident^ 

 really exist. Consequently, our type was I'egarded as being generically distinct, and the name 

 Euproops was proposed by one of us for it. Mr. Woodward, however, has since expressed the 

 opinion that these differences are probably of scarcely more than specific value. (See Geol. Mag., 

 Jan, 1868, vol. v., p. 2.) Without professing to have made an especial study of the fossil Crustacea, 

 on which Mr. Woodward is well known to be an eminently reliable authority, we would state that 

 we can scarcely doubt that a comparison of specimens would lead him to the conclusion that the 

 American form is at least subgeuerically, if not generically, distinct from Prestwichia." 



Finally the authors state that Euproops differs from Prestwichia "not only in the position of 

 the eyes, and the form and size of the glabella, or central ai'ea of the cephalothorax, but in the 

 entire arrangement of the ridges and included areas of the same." Fig. 9. is from an electrotype 

 of a cut published by Messrs. Meek & Worthen in illustration of their genus Euproops. 



rff-m ^ 



Fig. 9. — Euproops dance. M. Si.'W. 

 After Meek. 



Fig. 10. — Prestwichia roUtndatus. After 

 Woodwai'd. 



After repeated examinations of the series of about a dozen specimens from the collections of 

 Messrs. Lacoe and Carr, I am at a loss to find valid characters for the genus Euproops. In one ex- 

 ample of P. dance, the glabella or middle lobe of the head, is distinctly divided into four sublobes, 

 as in Woodward's figure of P. rotnndatus; again the lack of lateral abdominal spines in his figure of 

 P. rottindatus appears to me to be due to the imperfect state of preservation of the specimen, as 

 some of the Illinois specimens do not show them ; again the spines projecting from the sides of the 

 glabella over the base of the abdomen, and represented as wanting in Woodward's figures, are 

 wanting in certain Illinois specimens. As to the position of the compound eyes in P. rotundatus 

 as represented in Woodward's figure. I am inclined to believe that the author and artist have been 

 in error. I should not venture to make such a statement if in our Illinois and Pennsylvania 

 specimens of Prestwichia and Belinurus the position of the eye were not invariably on the outer 



•"On some points in the structure of the Xiphosnra, etc.. Quart. Jonrn. Geol. Soc, Feb. 1867, 



