16 PROCEEDINGS OF THE NATIONAL, MUSEUM vol. 78 



enough to find good specimens. If it really has, as the writtcrs sug- 

 gest, a truncated venter the distinction from Epengonoceras is very 

 tenuous. 



In the meanwhile the writers have accepted Epengonoceras as 

 distinct and have referred to it the specimens from the Aspen shale 

 here in question. Spath placed in his genus, beside the genotype, 

 Sphenodiscus cf. pedemalis (Von Buch) of Grossouvre^' from the 

 Cenomanian of St. Croix, later named Metengonoceras douvillei by 

 Grossouvre.^** Here probably belong also the Cenomanian form 

 named by Grossouvre ^^ Metengonoceras arnaudi and the Turonian 

 M. tolveie?ise, both from France. Here would go also Hyatt's M. 

 acutv/ni *° from the Eagle Ford shale of Texas. The range of the 

 genus in Texas appears to be from beds containing true Acanthoceras 

 and other Cenomanian forms up into beds containing Turonian 

 species of Metoicoceras and other lower Turonian forms. 



EPENGONOCERAS ASPENANUM, new species 



Plate 1, Figure 15 ; Plate 2, Fisxires 2-5 ; Plate 3, Figures 5-7 



This species is based on eight specimens, six of them flattened and 

 somewhat distorted molds of the exterior, one a free fragment of a 

 whorl, and the eighth, chosen as type, a flattened internal mold 

 preserving the beginning of the living chamber and showing the 

 sutures. 



The shell was in all probability a much compressed disk as in other 

 species of the genus, though the specimens in hand were so much 

 flattened in preservation that it is not possible to compare the form 

 with that of undistorted material from Texas and elsewhere. The 

 venter of the type at about 40 millimeters diameter is 1.5 millimeters 

 broad and flat with sharp margins ; at 60 millimeters it is 1.75 milli- 

 meters broad and still flat; at 73 millimeters diameter, the maximum 

 preserved, it is still evidently flattened but the distortion of the 

 specimen makes a measurement valueless. The umbilicus is 5 milli- 

 meters wide at the diameter of 70 millimeters and as shown on 

 several paratypes had a rounded shoulder and gently sloping inner 

 wall. Living chamber and aperture not seen. 



The surface of the shell, as shown in the type and plaster casts 

 made from the paratypes, was nearly smooth. No nodes are shown 

 and no folds, a few exaggerated growth lines of falcate form being 

 the only ornament. The type and one of the paratypes bore an 



" De Grossouvre, Albert, Les ammonites de la Crale sup^rieure : Carte gfiol. France 

 M€m., Recherches sur la Craie supgneure, pt. 2, PaMontologie, p. 140, text fisr. 58, 1894. 



»* De Grosseuvre, Albert, Le Cr4tac6 da la Loire-Inf6rieure et de la Vendi5e: Soc. sci. nat. 

 Guest France Bull., scr. 3, vol. 2, pp. 34-85, pi. 3, flg. 2, text fig. 6, 1912. 



8» De Grossouvre, Albeit, idem, pp. 35-37, pi. 3, flg. 4, text figs. 7-8, 1912. 



«> Hyatt, Alpheus, U. S. Geol. Survey Men. 44, p. 184, pi. 26, fig. 8 ; pi. 27, figs. 1-2. 



