nlMSTllnl'AIMA 



niiliiii'iit'trii or iiLo-at. Thnr.i.f ///// //,/, 

 small and offi-n- */ /////.-. Cambrian. 



The genera .ompri.-ed under this family piv-.-nl a numl. 

 characters, such as are displayed <.nly in the larval -tagi-s of higher fonn 

 cheeks are narrow and marginal, and may 

 be compared with those in the m-pinni. 

 stands of Sao and /'///,Yiy*'f //(>. K\e- ha\.- 

 not been detected, but the presence of an 

 eye-line sugge.-ts their possible e\i-tenee. 

 The variations in the glabella are very 

 marked, and are a> great as those whidi in 

 higher forms attain some importance a- 

 family charaderi-t ic& 



So far as known, all the larval forms 

 in the other families of the Opitthopana 

 agree in having the narrow marginal free 

 cheeks, hearing the genal angles. The eye- 

 line is present in most of the adult Olenidae, 

 and in the early stages of all so far as 

 known, so that the general average of char- 

 acters in the Conocoryphidae represents the conocoryphe &/.:/;, sciii..tii. 



main larval features throughout the other Without ti^e free cheeks. Cam- 



D r i a n ^rj t. c-y ; VJT i n 6 1 z, 



Fi... l-.-.M. 

 < I'lKilunof Atop* 



families. Bohemia.^i/i. 



Conocoryphe, Corda (Conocephalites, 



Barr.), (Figs. 1289, 1290). Cephalon semicircular; genal angles produced into spine- : 

 glabella distinctly lobed, wide behind and contracted in front, not extending to the 

 frontal border. Fixed cheeks very large, with conspicuous furrow parallel -to the 

 anterior margin ; free cheeks narrow, marginal ; thorax of fourteen segment- Cam- 

 brian ; Europe and North America. 



Atops, Emmons (Fig. 1291). Differs from Conocoryphc in having a more cylin- 

 drical and longer glabella, small pygidium, and >eventei-n free -egments. Lower 

 Cambrian ; North America. 



Ctenocephalus, Corda. Like Conocortjjiln', but with a lobe in front of the glabella, 

 which is also less strongly denned ; free cheeks larger ; pygidium much smaller: five 

 segments fifteen. Cambrian; Europe and North America. 



Bathynotus, Hall. Differs from Atop* and Ci.n><>,-<,riiji}n' in it.- wider a\i- : fre.- 

 cheeks united in front and extending backward into long genal spines ; thoracic seg- 

 ments thirteen ; pleura hastate. Lower Cambrian : Noith America. 



Family -2. Olenidae. Salter. 



Cephalon larger than the p<j<i f>!i'mn , //>/////// ////// tl,,i In,,,/ ,,,,},,! ,//y,//. - 

 produced into spines', free clweks .-- 1><: /'/'. Facial stiti'ri extending forward f/'"in (If 

 posterior margin of cephalon along the eye-lobes, and either ruttimi >},< anterior margin 

 separately, or meeting on the median line. Eyes crescent i<\ reniform, or 

 situated at the ends of eye-lines in all but the highest genera. Trunk /'<///, rum posed of 

 from eight (?) to twenty -six free segments. Pijiinlnnn frequently ."mull : marg 

 spinose. Principally Cambrian, but extending also into the Onlovidan. 



Paradoxides, Brongt, (Figs. 1292, 1293). Glabella enlarging in front, lobes 

 denned; thorax with from seventeen to twenty free segments, pleura with >pinif..rm 

 or hastate extremities; pygidium a small plate-like termination of the axis, seg- 

 mented. Individuals sometimes attaining a length of OG m. or more. Very abundant 

 in the Middle Cambrian of Europe, North America, and Au-ttalia. 



