122 THE DEVONIAN OF MISSOURI. 



Platyceras cf. erectum Hall 



Flate 26, figure 8; plate 28, figure 3. 

 L843. Acroculia erecta Hall, Geol. N. Y., Pt. IV, p. 174, fig. 6 on p. 172. 



1861. Platyceras erectum Hall, Descriptions of New Species of Fossils, p. 4. 



1862. Platyceras erectum Hall, 15th Rep. N. Y. State Cab. Nat. Hist., p. 32. 



1876. Platyceras erectum Hall, Illustrations of Devonian Fossils; Gasteropoda, pi. 2. 



1879. Platyceras erectum Hall, Pal. N. Y., vol. V, pt. 2, p. 5, pi. 2, figs. 4-11. 



1901. Platyceras erectum Kindle, Indiana Dept. Geol. Nat. Res., 25th Ann Rept.. 



p. 728, pi. 19, fig. 7. 

 1909. Platyceras erectum Grabau and Shimer, N. Am. Index Fossils, vol. I, p. 683, 



fig. 963a. 

 1913. Platyceras erectum Prosser and Kindle, Maryland Geol. Survey, Middle and 

 Upper Devonian, pp. 296-297, pi. 37, figs. 1-3. 



Prosser and Kindle' s description — "Shell regularly arcuate to the inrolled spire; 

 nearly two volutions; the spire at the apex closely inrolled'for about one and one-half 

 volutions beyond which the-body volution expands somewhat rapidly; the aperture often 

 spreading, not infrequently oblique with a sinuate peristome. Surface marked by 

 closely arranged, revolving, lamellose striae, which, upon the lower half of the body 

 volution, are abruptly arched along narrow bands, corresponding with former sinuosities 

 of the aperture." 



Remarks — Small specimens of the form referred to P. erectum are abundant but large 

 specimens are rare. 



Occurrence — Mineola of Montgomery and Callaway Counties. 



Platyceras cf. nodosum Conrad 



Plate 28, figures 4 and 5. 

 1841. Platyceras nodosus Conrad, Fifth Ann. Rep. Pal. N. Y., p. 56. 

 1859. Platyceras nodosum Hall, Nat. Hist. N. Y., Pal. Ill, p. 473, pi. 115, figs. 1-6. 



pi. 116, figs. 1-4. 

 1876. Platyceras dumosum and P. dumosum var. rarispinum Hall, Illustrations of 



Devonian Fossils; Gasteropoda, pi. 5 and 7. 

 1879. Platyceras nodosum Hall, Nat. Hist. N. Y. Pal. V, pt. II, p. 17, pi. 7, figs. 4 and 5. 

 1913. Platyceras nodosum Ohern, Maryland Geol. Survey, Lower Devonian, pp. 469- 

 470, pi. 79, figs. 13 and 14. 



Hall's description — "Subfalcate, with numerous thick obtuse nodes. This is a 

 cast in sandstone, and the shell was probably covered with spines. Length two inches. 



Shell obliquely subovate; volutions contiguous, about two or three, very rapidly 

 expanding from the apex; summit of the spire on a plane with, or a little above, the outer 

 volution; aperture round. 



Surface marked by iound obtuse nodes and strong interrupted or tortuous lamellose 

 striae." 



Remarks — Most of our specimens are fragmentary and all are internal moulds. The 

 nodes are larger, lower and less numerous than in most specimens figured by Hall. The 

 shape seems to be very near to that of Hall's specimens. 



Occurrence — Mineola limestone of Montgomery' County. 



Platyceras annulatum n. sp. 



Plate 26, figures 12 and 13. 

 Shell subcorneal. Aperture nearly circular. Apex slightly incurved; body volution 

 expanding rapidly from near the apex. Margins incomplete. Surface ornamented with 

 six or seven concentric ridges on the top of which are many nodes or bases of spines. 

 Length 16 mm., breadth 14 mm. The complete diameter was probably greater. 



