Weno and Pawpaw Formations 141 



HORIZON: Weno shale and ironstone, abundant; Pawpaw clay and 

 sand, rare. Rare south of the Red River region. 



LOCALITY : This is the common nacreous Turritella of the Weno iron- 

 stone and clay at Denison, Gainesville, and elsewhere in the Red River 

 region. Locality 604, Frisco cut three-fourths mile north of Union Sta- 

 tion, Denison, Texas (type locality) ; 601, near Gainesville, Texas. 



DESCRIPTION: Shell turreted, steep, spiral angle 17 degrees; ten 

 or more volutions, straight-sided, sutures sharply impressed, angles of 

 volutions sharply rounded, surface almost smooth, bearing about fourteen 

 lightly tuberculate spiral lines of unequal height. Of these, ten lie on 

 the side of the volution and four below the shoulder. On the terminal 

 volution of the type these are arranged as follows : 



Beginning at the suture, the first ridge is strongest and bears widely 

 spaced low obscure tubercles with flat spaces between; the thickness of 

 this rib equals the width of the space separating it from the second rib. 

 The second, fifth and seventh ribs are slightly narrower, but are ribbon- 

 like and low in proportion to their breadth and have slight nodular eleva- 

 tions widely spaced from each other. The other ribs are low, subequal and 

 have rounded tops and slight nodular elevations at wide intervals. The 

 last four ribs lying beyond the shoulder of the volution are relatively nar- 

 rower and more elevated than those on the flanks, and the inner three are 

 closely spaced, being separated by about the width of a rib ; the last rib 

 is more widely separated but is the same size. The rest of the volution 

 next to the umbilicus is smooth except for one or two obsolete spiral ribs. 

 In the intervals between the ribs mentioned there are three to five fine 

 equal raised lines. The transverse growth lines are prominent and sig- 

 moid, and resemble those in T. bravoensis Bdse, but are finer. Aperture 

 unknown ; crass-section of volution sub-quadrate, outer side straight, inner 

 side rounded. 



This species is separated from Turritella bravoensis Bdse, T. budaensis 

 Shattuck, and T. planilateras Conrad by having the tubercles very low, 

 and depressed, instead of coarse and prominent. It is separated from 

 T. leonensis Conrad, T. marnochi White, and T. denisonensis Cragin in 

 having a greater number of spiral ridges and more tubercles in each ridge. 



Cragin 1 describes without figuring, a variety under the name of T. kan- 

 sensis, which has less crowded revolving ridges than our species. Like- 

 wise, T. seriatim-granulata Roemer 2 differs from T. wenoensis in having 

 only five elevated tuberculated ridges, the middle one of which is flanked 



iCragin, Notes on some fossils of the Comanche series, Science, n. s., vol. 6, pp. 134- 

 136, 1897. 

 zRoemer, Kr. Texas, p. 39, pi. 4, fig. 12. 



