72 University of Texas Bulletin 



(Quenstedt) and H. quenstedti Uhlig. 1 The juvenile portion of the shell, 

 absent in the material at hand, may have been a close coil as in Macro- 

 svaphites, as indicated by the grooved impression on the long limb, but this 

 is not certain, and in addition the suture forbids identification with Macro- 

 scaphites. The suture and the absence of ribbing prevent its reference to 

 Ancycloceras. Bose 2 describes a similar Hamulina sp. from the Vraconian 

 limestone blocks of Camacho, Zacatecas. 



MEASUREMENTS : 



I (type) II III IV 



Length of fragment 7.8 mm. 10.0 8.9 8.1 



Width, lower end 1.6 1.0 1.5 1.7 



Width on bend 3.0 2.1 2.2 



HORIZON : Base of the Pawpaw formation, clay facies. 



LOCALITY : 714, near Fort Worth, Texas. The type and two other 

 individuals have been found here. 



Three fragments of a straight limbed ammonite, all lacking the aper- 

 ture and part of the larger limb, were found in the basal Pawpaw clay. 

 In the absence of better material their systematic position can not be set- 

 tled, and I assign them with hesitation to the genus Hamulina. The 

 curve connecting the larger limb is preserved, but this limb made no im- 

 pression on the inner face of the smaller limb, as in some Ptychoceras, 

 and therefore was not in close contact with it; in addition, the visible 

 portion of the curve is open, indicating a distant, possibly short, thick 

 limb. This might suggest Hamulina or Ancycloceras, which mostly differ 

 in their sutures and their prominent ribbing. Whether there were three 

 limbs as in Diptychoceras, is unknown ; however, the suture is very differ- 

 ent from, and less dissected than that figured by Gabb for his Diptycho- 

 ceras laevis (laeve) 3 and that species also differs greatly in form from 

 ours. 



Two other individuals (Plate 2, figures 23-25) show distinctly the curve 

 and the proximal portion of the shorter, thicker limb. This is free, and 

 is separated from the thinner limb by the space of about half of its 

 thickness. The aperture is not visible. One individual (Plate 2, figures 

 23, 25) shows also a part of the curve at the lower end of the slender 

 limb. This end turns with about the same curvature as that of the larger 

 curve, and on the venter of the lower end of the slender limb is a wedge- 



iPervinquiere, fit. pal. tun., Ceph., pp. 88-89. 



2 B6se, On some new Cretaceous Faunas from Mexico, Univ. Texas Bull, (in p'ress). 



"Gabb, Pal. Cal., II, pp. 142-5, pi. xxv, fig. 21a-b. 



