122 EXPLORING EXPEDITION FROM SANTA Ffi 



the exception of n portion of its upper beds, represent the Dakota group (No. 1) of 

 Upper Missouri Cretaceous series ; 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 Fort Pierre group and Fox Hills beds, N'os. 4 and 5 of the same. 

 The relations between the two sections will be more clearly understood by placing 1 

 the names of the several groups of each side l>y side ; thus: 



NEW MEXICAN CRETACEOUS SECTION. UPPER MISSOURI CRETACEOUS SECTION. 



7 T -r- /i ^ Fox Hills Beds, No. f>. 



Upper Division (lowest bed at least) < -,, , ,,. , , XT . 



I Fort Pierre Group, No. 4. 



-.-. T 11 lv . . ( Niobrara Division, No. 3. 



Middle Division < v , 7 T . XT 



( rort Union Group, No. 2. 



Lower Division Dakota Group, No. 1. 



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

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

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

 remains from the Lower Division are, Exogyra colmiilcJhi, M.; J'/icatida arcnaria, M., 

 Pinna (fragments), Gervilliat (fragments), (lri/]>li'a (undetermined fragments), and 

 Prionotropis Woolgari* ( Ammonites percarinatiifi, II. & M.). 



The following is a list of the species described and identified from the Middle 

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

 writer from these collections, viz: Ostira congesta, Conrad, 0. lugubris, Conrad, 0. tu/i- 

 formis, M., GrypJuea Pitcher i, Morton, Exogyra arictiua, Roemer, E. lamusculit, Roemer, 

 E. columlclla, M., Anomia nitida, M., Caprothui h'n-oni'is, M., Inoceramus fragUis, Hall & 

 Meek, I.prolli'mat/ci<s,$c}i\othe'un (sp.),7. lutit*, Mantel!?, CraxsateUaShiotuirdi,^!.., Ci/pri- 

 meraf crassa, M., Turritella Leonensis, Roemer, Pridi/nci/cltix? Mac<til>'i,-\ M., .Prioi/n/nt/t/.^ 

 Woolgari, and Scapliites larwrformis, M. & II. 



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

 in New Mexico, Kansas and Nebraska, viz., Ox/rca coi/f/i'xta, Inoccramus )>roUcmuti- 

 cus, I. fragiUs, I. latus f, Scaphites larv&formis, 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 Inoccrtinin* problematicue, I. Idtttx, and .Priotio- 

 tropis Woolgari occur in Europe. 



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

 Avicula Nebrascana, Evans & Shumard, Callista Dcivcyi, Meek & Hayden, Cur/Hntit 

 belhtlum, M., Ancliura ? Neivbcrryi, M., Baculitt'* di/<ri>x, Lamarck ?, and Placcnticcras 

 placenta, Dekay (sp.). 



Avicula Nebrascana, Callista Deivcyi, Ihicnlile* <ut<-e/>* ?, and J'l(U-t'>iti<rnix ]>lccnfa 

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

 sponding horizon on the Upper Missouri; and I'/itm/tim-a* plnci'iilu also occurs in the 

 same position in New Jersey and Alabama, while Baculitcs <tmr/< also occurs in New 



* The name 1'rioiioii'ofiix ].roji<>s<'<l by IMC in the Paleontology of the Uppi-r Alissouri, now (NovcinlxT, !>?.",) in thr 

 press; the American form there referred to JYionofropi* Woolgari, Mantel], being the type. 



tThis generic name was proposed by mo in Ilayden's Report of the Geological Survey of the Territories in 1872- 

 296 (foot-note), and the genus is more fully described in the Paheoutology of the Upper Missouri, now in the press. 



