36 Hill Paleontology of the Trinity' Division. 



Tire smallest and largest forms are void of the handsome rows 

 of tubercules which distinguish the specimens of medium size. 

 The larger adult specimens sometimes attain a length of two 

 inches. 



This form is of interest hecause it is the characteristic species 

 of the Wealden (Lower Neocomian) beds of Europe. It may 

 be the same as Melania strombiformis, first described from the 

 Wealden strata of North Germany by Schlotheim. 



De Verneuil and De Loriere, in 1886, published most excel- 

 lent figures and descriptions in their paper upon Materieux pour 

 le Paleontologie de 1'Espagne, entitled " Description des Fossiles 

 du Neocomien Superieur de Utrillas et ses Environs," Paris, 

 1868. They review the literature of the species and refer it to 

 the Vicarya, a subgenus of Cerithidx. They make four distinct 

 species of their specimens, which I believe to be variations of 

 the same species, all of which except one occur in intimate asso- 

 ciation in the lower Glen Rose beds. 



Professor Jules Marcou, in the previously mentioned review 

 of my Arkansas species, asserts that the form is a Nerinsea, but 

 the forms are absolutely void of the characteristic folds which 

 occur upon the columella of that genus, and hence he is mis- 

 taken. 



The form occurs in great abundance at the gypsum bluifs of 

 the Little Missouri, in Arkansas. At the plant bed locality near 

 Glen Rose, Texas, it is still more abundant and shows the variety 

 helvetica and lujani preserved together in great masses. At Post 

 Mountain, near Burnet, Texas, the badly worn shells of this 

 species occur in an agglomeration ten feet thick (plate v, fig. 

 7), void of other species and embedded in a matrix of the min- 

 eral grahamite. In this mass all the varieties can be found in 

 association. 



Nerinaea austinensis Roemer. 



Roemer. Paleont. AbhandL, vol. iv, p. 2 ( .)5, plate ol. fig. S. 



Fragments resembling this species are abundant in the upper 

 or Mount Bonnel beds of the Glen Rose beds, but are so poorly 

 preserved as to render their assignment to it only provisional. 

 I have found them in the Strontionite beds of the Colorado sec- 

 tion, and a stratum of the beds near the summit of Mount Bon- 

 nel consists almost entirely of calcified Ncruieas, In outer 



