i GO EH \ i r 



:lllt llors :IIK| MX I have in \ self assumed ; lull there max be. 

 tion of tin- aeenraex ofthU refe rem -c. ae tin- l.-ittcr hi-h.i, 



t In- A in:ili he.-e. [Relative to the cretaceous PhylloceraticUe it i> 



Jo In- olcr\cd. that :i lariv p:irt of tin- form-* docribed b\ 

 d'()rbio||\ were founded mi \.iin- specimens, which h:i<l not \ ct 

 developed the >|ccilic characters and which niiisl t herefore be 

 wit hdrawn. In regard lo -ome of ihc lii<li:in r<>nn- <lc-ci-il>c<l 

 MS llctcrophvlli liy St<>lic/k;i. I :iin not ccrt.-iin th:il they Ix-loiii: 

 to riujlhi' nit on Mccount of the imperfect reproeiil ;i! ion of the 

 Inlies ; in the hot cliniMte of 1 1 id in tin- oily l:iyer with which t he lith- 

 ographic rock^ are covered alw;i\>- liccoino -oincwii.-il ^ofteiicd. 

 so that the more minute Iei:iils are ofleii lost. 



Seventy-seveB species: Tria>. .hira. ( 'retaccon>. 

 PJIVI, OOOULTUM, Mojs. '\\ 111), ti--. ills. \\\\\. 



Family IV. .K(i( >< 1 K II ATI I) .K. 



The forms, which can IK- ti'aced from ^Egoceras, present >nch 

 manifold ehai-acleristics. it is not possible to even otter one posi- 

 tive character, with the exception of t he attached cover of the 

 indumental uland. which indeed, has been observed only in a 

 limited number of species, but in forms belonging to most of the 

 included groups. All the forms also, which we know, have the 

 lobes toothed all around, but by which, to be sure, t he possibility 

 of the existence of a stem form with simple sutures is not 

 excluded. 



The ^voloLiically oldest forms arc those of the M iischelkalk, 

 the atlinity of which with those of the Lias Ucyricli was the first 

 to apprehend ; t hey are absent in the upper Trias in almost all 

 the yet known localities and a^ain appear first in the uppermost 

 Strata in .K<j<n-vras planorboides. At the lu'^innin^ of the 

 Jurassic they attain an ext raordinary development, the details 

 of which will be described. 



l-'roin the meat extent of the family it is perhaps better to 

 subdivide them in the following manner: 



1. .K'.oi KI; \TI vi; :-.//'/'", /v/s, J /////>. 



2. II AKI'OCKKATI N .]. ; J/tl r f >n<-,' rtl * . ( ) / >] K'l I (I , Hllf '/<>< ; /</.< . 



-St<'l>li<ln<;T<i*. < rO8, -I /"!// 



/s. > 



