Stanton.] XENOPHORID.E. 133 



described as a new species and referred to Cassiope, which according 

 to the manuals of Zittell and Fischer is a synonym of Glauconia. 



In the more recent collections from Coalville there are several exam- 

 ples that unquestionably belong to Meek's species and yet they possess 

 the umbilicus and other characteristic features of Cassiope ivhitfieldi. 



The surface ornamentation varies considerably in different individ- 

 uals. In some examples each whorl of the spire bears five well marked 

 revolving ridges, two of which are adjoining the suture above and 

 below, respectively, while the other three are close together in the mid- 

 dle of the whorl and the lowest of them is the largest, giving to the 

 whorl its angular appearance. In other specimens, especially very 

 large ones, one or both of the ridges immediately above the angle is 

 obsolete. 



Turritella martinezensis Gabb, from the Cretaceous of California, 

 resembles this species quite closely both in form and ornamention, but 

 it is not umbilicate. 



Locality and position. — Near the base of the Cretaceous section at 

 Coalville, Utah, and at various localities in southern Utah. 



XENOPHORID^E. 

 Genus XENOPHORA Fischer von Waldheim. 



Xenophora simpsoni n. sp. 

 PL xxix, Figs. 4-6. 



Shell small, trochiform, consisting of four or five volutions; spire 

 moderately elevated with straight sides; periphery of last volution nar- 

 row, angular and somewhat produced; base nearly flat, with a rather 

 small but distinct umbilicus. The aperture is very oblique, irregu- 

 larly oval in outline, and with the inner lip slightly thickened. Surface 

 of the spire marked by numerous faint, irregular pits and depressions 

 that seem to have been caused by the adhesion of small pebbles and 

 bits of shell in the manner that is characteristic of this genus. These 

 irregularities of the surface are shown on internal casts almost as dis- 

 tinctly as on the shell itself. The surface also shows lines of growth 

 that are especially prominent and strongly curved on the base of the 

 shell. 



Height of one of the largest specimens, 10 mm ; greatest breadth, 

 16 mm . 



There is no other described species in the American Cretaceous with 

 which this need be compared, though comparisons with recent species 

 show that it certainly belongs fco Xenophora. There are 21 specimens 

 in the collection, all more or less imperfect, but taken together they 

 show all the characters of the species. 



The name is given in honor of Mr. Charles T. Simpson, of the U. S. 

 National Museum. 



