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K;imi 



ly6. 



ARTHROPODA 

 Raphiophoridae Angel 



PHYLUM VII 



Fifi. 1362. 



Ampyx nasutus 



(Dalmän). Or- 



dovician ; Pul- 



kowa, Russia. 



Ampyx portlocki Barraiide. 

 Ordovician (Etage D) ; Leiskow 

 Bohemia. x Vi (after Bamuide). 



. I. 7 u.'lnh,r1 cP,,halon without hrim, small, loide pygidium, and 



Hypoparia wüh Urgc tnlohed '^'V^^''^' T ^^^^^^-^ ;^^,,,,,. Small free cheeics 



visihle on the dorsal surface. Glahella 

 produced in front of the cephalon as a spme. 

 Ordovician and Silurian. 



Raphiophorus Angelin. Glabella obo- 

 vate, witli an abrupt apical spine. Five 

 thoracic Segments. Europe. 



Ampyx Bsilm!xn{Yig>^. 1357, i?; 1362, 

 1363). Glabella oval, terniinating in a 

 round spine. Six thoracic Segments. 



^ Duu^iw.«. ^ ,1V - Europe and North America. 



Lonchodomm Angelin. Glabellar spine long and prismatic in section. Europe and 

 North America. 



Order 2. OPISTHOPARIA Beecher. 



Free cheeks generally separate, always hearing the geml angles. Fadal sutnres 

 e.tendingforwardfror.t}u posterior part of the cephalon ,mtMn the f-f»;f2bem 

 cutting m anterior margin separately, or more rarey nmtmg m front of thegM^em, 

 Compound paired holochroal eyes on free cheeks, and well developed rn all hnt the most 

 primitive family. 



The families which are here placed under this order lend themselves quite readily 

 to an arrangement based upon the characters successively appearing m the ontogeny ot 

 any of the higher forms. Thus Sao, Ptychoparia and other genera of the Olenidae 



Fig. 1304. 



Cephala of the Opisthojxiria. A, Atops. B, Conocwyphe. C, Ptychoparia. D, Olemis. E, Asa2-)hus. 



F, lUaenus. G, Prwtus. H, Goldius. I, Lichas. J, Acidaspis (after Beecher). 



have first a protaspis 8tage only comparable in the structure of the cephalon with the 

 genera of the preceding order. Therefore this stage does not enter into consideration 

 in an arrangement of the families of the Opisthoparia. In the later stages, however, 

 there is a direct agreement of structure with the lower genera of this order. The 

 nepionic Sao, with two thoracic Segments (Fig. 1355, B\ lias a liead structure agreeing 

 in essential features with that in Atops or Gonocoryphe (Figs. 1364, A, B). A later 

 nepionic stage, with eight thoracic Segments (Fig. 1355, G) agrees closely with the 

 adult Ptychoparia or Olenus (Fig. 1364, 0, D). These facts clearly indicate that the 

 family Conocoryphidae should be put at the base of this extensive order, Moreover, 

 as Ptychoparia Q.ndi Olenus are more primitive and simpler genera than Sao, they, as 



