NO. 7 PTYCHOPARIID TRILOBITES — RASETTI I3 



ing inward as in other species of the genus. Posterior branch turning 

 backward in a wide curve. Surface of test covered with fine granules 

 with larger scattered granules both on glabella and fixed cheeks. 

 Length of largest cranidium 7.5 mm. 



Remarks. — The species is assigned to Antaguuis with a question 

 mark because it departs from the type species in three features which 

 might be considered of generic importance : the almost complete dis- 

 appearance of the medial preglabellar field, the narrowness and down- 

 ward slope of the palpebral area. Nevertheless, since the shape of the 

 glabella, direction of the facial sutures, and structure of the frontal 

 border are typical of Antagmus, the species may be provisionally 

 placed in that genus. 



The species was found associated only with an undetermined 

 Onchocephalus and another undescribed form ; hence the evidence for 

 its Early Cambrian age is not entirely conclusive. However, the fact 

 that a cranidium of this species in the U. S. National Museum was 

 collected at Bic, where boulders of other than Early Cambrian age 

 are virtually unknown, supplies additional proof. 



Occurrence. — Boulder M-9, Metis. Also an unknown boulder at 

 Bic. 



r3;/>^.y.— Holotype : U.S.N.M. No. 123860. Paratypes: U.S.N.M. 

 Nos. 1 23861 -2. 



EOPTYCHOPARIA Rasetti, new genus 



Description. — Glabella of regular convexity, rounded in front, show- 

 ing three or four pairs of shallow glabellar furrows. Frontal area 

 well divided into preglabellar field and border, usually of equal lengths 

 (sag.). Marginal furrow regularly curved or with a slight median 

 inbend caused by an expansion of the border. Palpebral area some- 

 what convex, horizontal to slightly downsloping, 0.5 to 0.7 times the 

 width of the glabella. Palpebral lobes about one-third as long as the 

 glabella, at the level of the glabellar midpoint. Posterior limbs about 

 as wide (tr.) as the occipital ring, with furrow reaching the distal 

 end. Anterior facial sutures slightly divergent ; posterior branch as 

 in Antagmus. 



Type species. — Eaptychoparia normalis Rasetti, new species. 



Remarks. — The features of the species attributed to the genus are 

 about average for Lower Cambrian ptychopariids ; hence the genus 

 is difficult to characterize and intergrades with Antagmus, Piasella, 

 and Onchocephalus. Eoptychoparia essentially corresponds to Res- 

 ser's and Lochman's conception of Ptychoparella as based not on the 



