II M'l 



!HM|\ chamber ( l/llftl. jil,,., . n . \ '11111.. 



. ZeusohiN 



In certain i.pper .Jurassic form->, *\hich are allied to //fij>/. 

 . the sculpt iin- gradually passes from tin- external 

 over tO the flankfl in feebly undulating rib hown in 



ih-ntnt. /ill.; better de\ eloped in /A//,/. //;,///,//. 

 Opp. : and this feature is repeat ed in Iliifil. <li 'Jfiri'i', ( )rl.. (' 

 ( h'b.. hi.-iirruhini. Lrvin. 



Finally, ^jx-cics of ////y//ocr/v/x :ipjn-:ir which :irc dist rilmtcd 

 in tin- (Yct.-ircoiis. with constrictions rc;icliiiiu Inrwjirds ( Iltijil. 

 /a, if/. /'nrruiHlii-ri). :i peculiarity with which I have not met 

 in any .Jurassic form: the iniirr whorls here serve assure iniidcs. 

 tVoin the a^n-eiiH-nt. of the lobular niarlvin.iis, sin<-c they 

 a typical //a/i/orcm* with entirely smooth whorls. 



With these furrows a sickle-shaped undulating radial sculpture 



idually combined, and a izronp of forms results, of which 

 the principal type is //<ij>l. [ila n ulhi in, Sow. 



In spite of this iiTeat niaiiifoldness, it is very easy to distin- 

 guish the represenlatives of JJaploceras from strata which are 

 lower than the Turonian and downwards, by their whole habitus 

 and lobes, yet nothing is more difficult to express in words. 



The numlcr of lobes in Ha^lnr^rfi^ varies, since besides the 

 siphonal lobe and the two laterals two to four auxiliaries are 

 present ; the lateral lobes are never symmetrically divided (a 

 diffrrenee from Li/focrras), and never present the characteristic 

 rounding of the saddle lobes of PhylloceraS] in the forms from 

 the Neoconiian the lobes are not yet very complicated, but later 

 are much brain-lied, with slender stems; the stems of lobes 

 mostly broader than those of the saddles, the first lateral not 

 strikingly larger than the second. 



If we compare the lobes of other forms, Srhhwitbarhia, Amal- 

 f/n't/*, PhyllocerOS, Lijt<-<'r<i* and Artinllnircnin are excluded 

 from consideration; a difficulty can only arise in regard to 

 Huj,lH,\<. which certain forms resemble in their lobular struct lire. 

 Only here the width of the lobes : nid bodies of the saddles will 

 seldom allow of a remaining doubt, since the latter are. M :i 

 rule, bi-oader than in the lirst, the stmn<r development of the 



nals.-iddle, the >t.rikin<r litlerence in si/e bet ween t he t w 

 laterals, linally the l-roader. better rounded forms of t he 



