128 rAr..E()NTOL<)(;v. 



This shell differs from all of the compressed, sharply-keeled ammonitoid 

 forms known to me, with a small umbilicus and curved costse, in the pres- 

 ence of the numerous little irregularly-arranged pimple-like nodes. As the 

 specimen shows no traces of the septa, it is not possible to determine which 

 of the numerous proposed groups it most nearly approaches in its internal 

 characters. 



The specific name is given in honor of Dr. Gustav C. Laube, of Vitnna, 

 the author of the beautiful Monograph of the St. Cassian Fosfils. 



Locality and position. — Same as last. 



Genus EUDISCOCERAS, Hyatt. 



e'r (augm. part.) ; iVWof, a quoit. ; Ktpai;, a boru. 



" This type is distinguished by its discoid form, open umbilicus, and 

 an abdominal keel, bordered by furrows and ridges, the latter being inter- 

 rupted or tubercular; the young with comparatively large pilae, growing 

 smaller and more flexuous in the adult, and finally fading away in the 

 larger half of the body-volution." — (A. H.) 



EuDiscocERAs Gabbi, Meek. 



Plate 11, figs, a and 3 rt. 



Shell compressed-discoidal, with the periphery narrowly truncated, and 

 having a narrow, very obscure, smooth ridge along the middle; umbilicus 

 shallow, equaling about two-thirds the breadth of the outer turn; volutions 

 flattened on the sides, and abruptly truncated around the umbilicus on the 

 inner side, each embracing apparently about two-thirds of the next within. 

 Sixrface with moderate- sized, rather distinct, bifurcating costae on the sides 

 of the volutions in young shells. As the shell advanced in growth, the 

 costae became smaller and more crowded, being merely coarsely linear on 

 the outer turns, where they curve first a little backward at the umbilicus, 

 then arch gently forward as they cross the middle of the sides, beyond 

 which they usually curve a little backward, and then very slightly forward, 

 as they abruptly terminate, so as to leave a nan-ow, smooth space between 

 their outer ends and the narrow periphery. Around each margin of the 

 latter there is also a row of compressed nodes arranged with their longer 



