Logan.] 



The Invertebrates, Fort Pierre Group. 



503 



other states. The following species have already been described 

 from the Fort Pierre : 



Hemiaster humphreysiana, 

 Ostrea patina, 



0. inornata, 

 Gryphea vesicularis, 

 Inoceramus sublaevis, 



1. proximus, 

 I. cripsii, 



I. incurvus, 

 I. convexus, 

 I. sagensis, 

 I. altus. 

 I. balchii, 



Pholadoinya hodgei, 

 Trigonarca exigua, 

 Volsella meekii, 

 Yoldia ventricosa, 

 Xemodon sulcatinus, 

 Nuculana bisulcata, 

 N. equilateralis, 

 X. obsoletiatriata, 

 Nucula planimarginata, 

 X. subplana, 

 Nuculata subnasuta, 

 Pteria fibrosa, 

 P. linguiformis, 

 P. haydenii, 

 P. nebrascensis, 

 Anomia subtrigonalis, 

 Syncyclonema rigida, 

 Chlatnys nebrascensis, 

 Gervillia subtortuosa, 

 Protocardia rara, 

 Lueina subundata, 

 Veniella subturnida, 

 Crassitella evansii, 

 Thetis eircularis, 

 Eriphyla gregaria, 

 Callista pellucida, 

 Neaera moreauensis, 

 Corbulamella gregaria, 

 Corbula crassimarginata, 

 Callista deweyi, 

 Tellina cheyennensis, 

 Mactra gracilis, 

 Teredo selliformis, 



Acma parva, 

 A. occidentalis, 

 Anisomyon alveolus, 

 A. patelliformis, 

 A. subovatus, 

 A. shumardii, 

 A. sexsulcatus, 

 A. borealis, 



Haninea subcylindrica, 

 H. occidentalis, 

 Dentalium gracile, 

 Entalis paupercula, 

 Odontobasis ventricosa, 

 Pasciolaria cheyennensis, 

 F. flexicostata, 

 Anchura sublaevis, 

 A. para, 



A. nebrascensis, 

 Aporrhais biangulata, 

 Trachytriton vinculum, 

 Margarita nebrascensis, 

 Closteriscus tenuilineatus, 

 Margaritella flexisticata, 

 Vanikoro ambigua, 

 Pyrifusus intertextus, 

 Amauropsis puludiniformis, 

 Actseon attenuata, 

 Baculites ovatus, 



B. compressus, 

 Ptychoceras mortonii, 

 Ancycloceras uncum, 

 Heteroceras cheyennense, 

 H. angulatum, 



H. cochleatum, 



H. mortonii, 



H. tortum, 



H. umbilicatum, 



Placenticeras placenta, 



Ammonites complexus, 



Phylloceras hallii, 



Scaphites nodosus, var. brevis, 



S., var. quadangulatus, 



S. nodosus, var. plenus, 



Nautilus dekayii, 



N. dekayi, var. montanensis. 



