29 



ENOHOSTOMA D. gen. 



[Ety. eiichos, sword; sioma, blade. J 



Shell smooth, elongate, lanceolate, transverse section more or less 

 rounded or narrowly subovate. Shell substance thin, solid, flexible, 

 horny, lime-phosphate. Type Enchosioma lanceolaium, described 

 as HyolUhes lanceolatus, S. A. Miller, 1892, advance sheets, 18th 

 Kep. Geo. Sur. Ind. p. 63, from the Chouteau limestone. 



When the species HyolUhes hinceolaius was described, only a 

 few fragments had been selected atd the specimen then illustrated 

 was supposed to represent nearly the complete length, but later 

 collections from Sedalia and Providence, Missouri, showed it was 

 not half the length of the original. We have a specimen now 

 before us two inches in length, which is broken off at both ends, 

 and the smaller end is as large as the smaller end of the type, 

 which is less than an inch in length. Another specimen at hand 

 an inch and a quarter in length, is larger at the smaller end than 

 the type is at the larger end. Another fragment an inch in length 

 is no larger at the larger end than the type is at the smaller end. 

 The evidence thus furnished shows that a complete specimen 

 would be three inches in length or even more than that, and that 

 the greater diameter at the larger end, is three-tenths of an inch. 

 We have examined about fifty fragments, none of them seem to 

 be complete at either end, but as none of them seem to contract 

 toward the larger end, we infer that the species does not contract 

 toward the mouth, as in Connlarin. The smaller end of all our 

 specimens, though in some cases, not exceeding one twenty-fiflh 

 of an inch in diameter, is broken off, so that evidently a perfect 

 specimen has an acute point. All of the specimens from the 

 apical end of the shell show a curvature, and the best specimens 

 show a curvature of an eighth or tenth of a circle. The apical 

 end is round in the best preserved specimens, but all of them are 

 subovate toward the mouth. As many of them are compressed 

 toward the larger end it is hai-d to tell the correct transverse 

 section, but from the large number examined, it is clear that the 

 section illustrated in fig. 36, pi. IX, of the 18th Eep. of the Geo. 

 Sur. Ind., is somewhat compressed. A normal section, probably, 

 becomes more and more acutely ovate as the mouth is approached. 



A few fragments on hand are longitudinally fluted, but if they 

 are normal, they belong to a distinct and undescribed species. 



The texture of the shell distinguishes this genus from the 

 Hyoliihadd' and brings it into some kind of relation to Conid<iria. 

 It cannot, however, be fairly classed with the Conulariidir trongh 

 properly falling within the order Conularida. We, therefore, pro- 



