158 PALEONTOLOGY OF ILLINOIS. 



Locality and position: Bockford, Indiana, in the Gonaititc bed of the Kin- 

 derhook group; also, in the same horizon at Grafton, Jersey county, Illinois. 

 Subcarboniferous. 



GASTEROPODA. 



Genus STRAPAROLLUS, Montfort, 1810. 



(Conch. Syst., ii, p. 174.) 



If we could rely upon the accuracy of Montfort's figure and description of 

 the type of his genus Straparollus ($. Dionysix), little doubt could be enter- 

 tained in regard to its being entirely distinct from Euomphalus, Sowerby, as 

 represented by Sowerby's typical species E. pentangulatus, E. catittus, and E. 

 nodosus. As Prof, de Koninck, however, after enjoying the advantage of study- 

 ing collections from Montfort's original locality (Namur), gives figures of S. 

 Dionysii, Montfort (Foss. An. Belg., pi. xxiv.), showing the form of the aper- 

 ture, and the nature of the lower part of the lip to be quite different from 

 what we see in Montfort's figure, and more nearly as in the types of Euompha- 

 lus, we are probably warranted in adopting the conclusion that these forms are 

 congeneric, and that Montfort's figures are, as usual, defective. Still, after ad- 

 mitting the correctness of Prof, de Koninck's identification, and the accuracy of 

 his figures, we can but regard the original types of Euomphahis, with their 

 greatly depressed or nearly planorbicular form, and angular whorls, almost 

 equally visible on either side, as at least subgenerically distinct from the type 

 of Straparollus, with its rounded or non-angulated whorls, smaller umbilicus, 

 and more prominent spire. Hence we think the name Euomphahis should be 

 retained, in a subgeneric sense, under Straparollus, for the group of which E. 

 pentangulatus, of Sowerby, is the type. 



We are aware Prof. McCoy, and some others, regard Euomphalus as typified 

 by E. pentangulatus, as an exact synonym of Straparollus, and that he proposes 

 to transfer the former name to another group, consisting of rough, Cirrus-like 

 shells, of which E. discoris and E. rugosus, Sowerby, are examples. (See 

 Brit. Pal. Foss., p. 279). It seems to us, however, that if the name Euompha- 

 his is to be retained at all, we should apply it to the forms for which it was 

 originally proposed, and that we have no right to transfer it to another type, 

 because Sowerby subsequently, in another place, refers this other type to his 

 genus Euomphalus. If we regard Straporollus, Montfort, 1810, and Euompha- 

 his, Sowerby, 1815, as exactly synonymous, then the latter name should be 

 dropped from use, except in the synonymy of Straparollus, and could not, 

 according to the most generally accepted rules of nomenclature, be transferred 



