122 EXPLORING -EXPEDITION FROM SANTA VK 



the exception of a portion of its upper beds, represent the Dakota group (No. i ) of 



Upper Missouri Cretaceous scries: also that his Middle Division occupies the same 

 horizon as the Fort Benton and Niobrara groups (Nos. 2 and 3) of the Upper Mis- 

 souri section; while the lower bed at least, of his Upper Division, represents appar- 

 ently a blending of the Fori Pierre group and Fox Hills beds, Nos. 4 and5ofthe same. 

 The relations between the two sections will be more clearly understood by placing 

 the names of the several groups of each side by side; thus: 



NEW MEXICAN CRETACEOUS SECTION. UPPEB MISSOURI CRETACEOUS SECTION. 



Upper Division (lowest bed at least) \ £°* \ { j) U B( £ 8 > ®°'£ , 



( rort 1 lcrre ('roup, No. 1. 



Middle Division J Niobrara Division, No. 3. 



I Jb ort I Dion Group, No. 2. 

 Lower Division Dakota Group, No. 1. 



The vegetable remains from the Lowei' Division of the New Mexican section (as 

 well as those from the others) have been investigated by Dr. Newberry, in whose 

 report the reader will find them fully described and illustrated. The molluscan 

 remains from the Lower Division are, Bxogyra columhella, M., PlicatuJa arenaria, M., 

 Pinna (fragments), GerviUia? (fragments), Gryphaq (undetermined fragments), and 

 Prionotropis Woolgari* (zzAmmonites percarinatus, H. & M.). 



The following is a. list of the species described and identified (Void the .Middle 

 Division, each of those followed by the letter M. being new, and described by the 



writer from these collections, viz.- Ostrea congesia, Conrad, 0. lugubris, Conrad, 0. uni- 

 formis, M., Gryphaa Pitcheri, Morton, Exogyra arietina, Roemer, E. keviuscula, Roemer, 

 /■/. columbello, M., Anomia nitida, .M., Caprotina bicornis, M., Inoceramus fragilis, Hall & 

 MVek, /. problematicus, Schlotheim (sp.), /. lotus, Mantel! ?, Qrassatella Shumardi, K.,Cypri- 

 mera? crassa, M., TurriteUa Leonensis, Roemer, Prionocychisf Macombi,j M., Prionotropis 

 Woolgari, smdScapMtes larvae/omits, M. & II. 



Of these eighteen species, the following are common to the rocks of this horizon 

 in New .Mexico, Kansas and Nebraska, viz., Ostrea congesta, Inoceramus problematic 

 cus, T. fragilis, I. lotus f, Scaphites larvaformis, and Prionotropis Woolgari None of 

 them, however, are known to occur in New Jersey, or at other localities east of the 

 Mississippi, in the United States; though Inoceramus problematicus, Llatus,a,nd Priono- 

 tropis Woolgari occur in Europe. 



BVom the lowest bed of the Upper Division, the collection contains specimens of 



Avicula Nebrascana, Evans & Shumard, CaUista Deweyi, Meek & Hayden, Cardium 

 beUulum, M., Anchura f Newberryi, M., Baculites anceps, Lamarck f, and Placentideras 

 placenta, Dekay (sp.). 



Avicula Nebrascana, CaUista Deweyi, Baculites anceps t, and Placenticeras placenta 



are common to this lowest bed of the Upper Division in New Mexico and the corre- 

 sponding horizon on the Upper Missouri: and Placenticeras placenta also occurs in the 

 same position in New Jersey and Alabama, while Baculites anceps also occurs in New 



The name Prionotropis propositi by me in the Palaeontology of the Upper Missouri, now (November, 1875) in the 

 press; the American form there referred to Prionotropis Woolgari, Mantell, being the type. 



tThis generic name was proposed by me in Hayden's Report of the Geological Survey of the Territories in L873- 

 293 (foot-note), and the genus is more fully described in the Paleontology of the Upper Missouri, now in (lie preBS. 



