JEG, ANID 1B) OO OC IE.. 
PLACENTICERAS. 
IGS lee oa eLACeNLICERcesISCmCamLOSCTSCmllny ab Uj eee ee eee eee 200 
Fic. 1. Section of a small specimen—‘‘passage form between this species and 
guadalupee.’” 
2. Side view of same. 
San Carlos, Presidio County, Tex.; San Carlos beds, Upper Cretaceous; Coll.U. 8. 
Geol. Sury. 
Wier G5, Jee NOGON TgBoaMaD, IBN 6556 ose-sceosochoossoseoosoeucsseassasesssecesassas 203 
Fig. 3. Side view of the type specimen. 
4. Section of same. 
5. Aperture view of same. 
Near Presidio Del Norte, Chihuahua, Mexico; San Carlos beds, Upper Cretaceous; 
Coll. Columbia University, No. 10073G. 
314 
