70 University of Texas Bulletin 



dissected; first lateral lobe narrow, laterally dissected, twice bifid term- 

 inally; second lateral saddle slightly broader, twice bifid; second lateral 

 lobe lower, simpler, bifid, dissected laterally; third lateral saddle low, 

 broad, rather simple, twice bifid; antisiphonal lobe very simple, rounded, 

 slightly trifid at tip, nearly twice as tall as broad. 



ANCYCLOCERAS BENDIREI n. tp. 



PL 11, fig. 1 

 1920: Hamites sp. B. Winton and Adkins, Univ. Texas Bull. 1931, p. 22. 



MEASUREMENTS: Diameter of shell without tubercles, dorsoven- 

 tral, at small end of fragment 19 mm., at middle of curve, 28 mm., at 

 large end of curve 25 mm. ; same diameters, right-left, respectively, 16.5 

 mm., 22 mm., 24.5 mm. Number of ribs in 5 cm. along straight portion, 

 7; on curve, 4; average number of dorsal costellae per centimeter, 6. 



HORIZON: Base of Weno formation, marl facies. 



LOCALITY : 618 (type locality) , middle exposure, about 10 feet above 

 the top of the Denton marl, near Fort Worth, Texas. The type, consist- 

 ing of three fragments, and a fragment of another individual were found 

 here. 



DESCRIPTION : Two limbs connected by a curve ; of these a greater 

 part of the thicker limb and a part of the thinner limb are missing. There 

 is not enough of the curve present to detect a spiral winding of the 

 coil. The smaller, ascending limb increases moderately in diameter to 

 the curve, where the fragment has its greatest thickness. There are 

 four symmetrically placed rows of prominent, rather slender spines, two 

 ventro-lateral and two mid-lateral. The spines of the two ventro-lateral 

 rows are coarser and are laterally flattened at the base ; those of the mid- 

 lateral rows are more slender and are circular at the base. These spines 

 are widely spaced, and a set of the four spines lies on each rib. The ribs 

 are coarse, remote, and in a plane nearly at right angles to the long axis, 

 however, they slant ventrally towards the aperture, and dorsally from the 

 last line of tubercles are continued as obscure elevations which cross the 

 dorsum as narrow, fine ribs. The four rows of tubercles bound three 

 flat longitudinal strips, one mid- ventral and two ventro-lateral; the re- 

 mainder of the circumference is evenly curved. The cross section of the 

 shell is therefore hexagonal in its ventral half and short oval in its dorsal 

 half. Shell and suture are preserved. 



