Mauylaxd Ceoi.ooical SltiVey 195 



Spirifeu tullius Hall 

 Plate XIX, Figs. 1-7 



Spirifera tullia Hall, 1SG7, Pal. N. Y., vol. iv, p. 218, pi. n5. fi.?s. 1-9. 



Spirifer tullius Hall and Clarke, 1893, Pal. N. Y., vol. viii, pt. ii, pp. 14, 35, 



pi. xxii, fig. 18; pi. xxxvii, figs. 6, 7. 

 Spirifer tullius Schuchert, 1897, Bull. U. S. Geol. Siirv., No. 87, p. 408. 

 Spirifer tullius Clarke, 1903. N. Y. State Mus., Bull. 05, p. 326. 

 Spirifer tullius Grabau and Shimer, 1909, N. Am. Index Fossils, vol. i, p. 



332, fig. 422e. 



Description. — Shell small, sTibelliptical, gibl)onp : hinge-line e(|iial or 

 greater than the width of the shell. Ventral valve gibbous, greatest con- 

 vexity above the middle of the shell, curving abruptlj^ to the sides and a 

 little flattened at the cardinal angles, mesial sinus sharply defined quite 

 to the beak, not deep, rounded in the bottom ; high cardinal area. Dor- 

 sal valve moderately convex; mesial fold Avell defined, wide below and 

 narrow above, flattened and sometimes depressed on the summit; sliell 

 curving gently to the lateral margins with slightly flattened cardinal 

 aneles. Surface marked by fourteen or more simple, low, flattened or 

 rounded plications on each side of the fold and sinus, which in exfoliate.] 

 specimens are frequently subangular; the entire surface marked by fine 

 continuous radiating striae, which are most clearly shown on tie inter- 

 vals between the plications and on the fold and sinus. 



This species resembles somewhat young specimens of Spirifer aiidacu- 

 Iks: but is distinguished by its more gibbous form, more nearly parallel 

 lateral margins, broader jjlications and especially by its conspicuous ra- 

 diating striae. JTall reported this species only from central Xew York; 

 but since then its occurrence has been noted in Erie County, New York, by 

 Professor Grabau,^ in eastern central and eastern New York by the 

 writer," while Professor Whiteaves has reported a variety of the species 

 from the Athabasca River in British America.^ 



' Bull. Buffalo Soc. Nat. Hist., 1899, vol. vi, p. 208. 



= 15tli An. Rep. State Geol. N. Y., 1895. p. 129; 17th ibid. 1899, p. 202; Bull. 

 U. S. Geol. Surv., No. 120, 1894, p. 41. 



" Cont. Canadian Pal., vol. i, pt. iii, 1891, p. 224. 



