M'Koriloi: HI' | i; \-. |.i T" \i 



Abdomen, over whiob tin- pihe do n>t pa--. sh.,u- that this ia .- 



di lie rent irenns. rharacteri/ed by :i l Hie rent nio< le . .1 ' < |e\ ei< >pment . 

 Tin- septa are quite simil:ir to I ho-e of '/'/v/'7/ //''/'/s. Imt it i- 

 ,\(i\ evident that in the Traeh\ eer.-il id;e the -epta cannot l>e 

 lM.knl tn for Lienerie liHerel)e'N. (iiv.-it .lillel-elice^ :il-.. OOOO1 

 ill the MiMomit of involution of the (litlereiit s|n-eie< :inl in the 

 development of t heir extern:il e|i:ir:i-ter>. 



(i. ROTKI.I.IKOMMK, Meek. I'l. Id."). li^>. 592, '''. TH.M-. 



'\'\{ \\>\\\ OEBA8, 



T. WHITNEYI, Gabb. IM. 105, figs. 590, 591. Trias. 



Nevada ; California. 

 K.-imily I'HVSANOIDJE. 



AeiiocHoHDieKKAS. Myjitt. Tills oenti> i> closely :illie<l to 

 Li/fn,; /v/s mid /'/ii/Hor-cras. Suess, mid //fi/ilorrrn* of Xittel, 

 eoinlnnini:- characteristics \vliielj :ire t'oiind in all of these. In-side- 

 hnviiio- peculiar characters of its own, and a different develop- 

 ment. The extent of involution is comparable with that of 

 /A//*/or/v/>-. but the whorl itself is about intermediate between 

 the extreme roundness of Lytoceras and the more flattened sides 

 of Phyllocr.rn,}*. Its peculiar characteristics consist in having 

 larov lateral tubercles and abdominal pil;e, which are united as 

 they near the tubercles. The smooth zone along the centre of 

 the abdomen in the yoim<r is also probably of <renerie. value. 



A. HYATTI. Meek. PI. KM;, lipr. ;,<.i4. r |^,-ias. Nevada. 



Genus EUTOMOCERAS, Hyatt. 



r !1iis is a well-marked type, characterized by its lenticular 

 form, narrow umbilicus, apparently at all age> very -harp ab- 

 dominal keel, without furrows or lateral ridges, and small, regu- 

 lar arched pihe on middle si/rd specimens, growing wider, more 

 irregular, less distinct, and developing small lateral lobes on the 

 adult, with both nodes and pihe becoming obsolete on the la 

 part of the body-volution. 



K. LAI r.Ki. Meek. I'l. KM;. iin->. 595, M;. Tria, Nevtnl.i. 



'fhe family relations of the above, as well as of the following 

 genus an- not in<licated. 



