Descriptions of Species. 35 



Tiirritelht Iwlrciico Pictet and Renevier. Mater, pour la paleout. 

 Suisse du ter. aptien, 1854. 



Qissiope helvetica H. Coquand. Monogr. paleout. de I'et. ai)tieu 

 de I'Espagnc, 18(iG. 



Ccrithium lujani Verneuil. Bull, de la Soc. Geol. de France, 

 2e liv. Tome x. 1853. 



Cerithimn laxani Verneuil. Memoria geognostica de Castellou 

 par Vilanora, 1859, i:)late iii, Fig. 7. 



Cassiope verneuilli H. Coquand. Monogr. paleont. de I'et. apt. 

 de I'Espagne, 1S6G. 

 • Murex strombifoniiis Schlotheim. 1820, Petrefact., p. 144. 



Muricifes stromhiformis Schlotheim. Monographic der Nord- 

 deutschcn Wealdenbilduug, Dunker, 1846, p. 50, pi. x, fig. 18«, Jk 



This form is indistinguishal)le h'om the figures of V. lujani and 

 ]'. hdcctica of De Verneuil and De Loriere, but without conqtari- 

 son of type specimens their identity cannot be positively as- 

 serted. V. lujani is descriljed as follows : 



"Shell elongated, with thick test; S]iire regular, straight, or 

 sometimes a little pupoid; ten or twelve turns of the spire. 

 Eacli turn of the spire is marked by numerous sinuous cross- 

 stria\, strongly bent inward uj^on tlie first anterior quarter of 

 each spiral. The sutures are generally well defined." The 

 whorls are also usually marked by two longitudinal elevated 

 Ijands, one near each border, which in the apical whorls and 

 adult specimens appear as plain elevated bands, or maybe in 

 the lower two-thirds of the shell nodular. They coutinue upon 

 the buccal face or base of the shell as bands. " The Ii[> always 

 presents at the posterior or upper end a pronounced gutter. The 

 outer lip has a deep, broad indentation corresponding with the 

 termination of the basal suture line beneath the last carina or 

 row of tubercules. The inner margin of the labial opening is 

 thickly encrusted." — De Verneuil. 



This is one of the most abundant, variable, and characteristic 

 forms of the Trinity Division, occurring in the lowest molluscan 

 horizons of the Glen Rose 1)eds tliroughout its extent from An- 

 toine, Arkansas, to the Colorado river in Texas. It was first 

 figured from America by the writer in his report u[)on the Cre- 

 taceous l)eds of Arkansas under tlu; name Plenruccra stroiiihl- 

 J'onitl-s Schloth., after Zittel. Although a very al)undant form, the 

 oral aperture was only recently discovered, it having hitherto 

 been Ijrokeu in the delicate structure of the specimens, and the 

 generic position thereby made uncertain, as is attested by the 

 widely different genera to which it has been referred in Europe. 



