Ka 71:', 



Nllou* vl|tilii%.) 



margin, l-acial suture-; making a l.road out ward curve mi th-ir anterior liinli. 

 incurving a^ani near the anterior margin. reaching it in front of the center of tin- 

 eyes and trauM-sintf tin- margin without angulat ion: posterior curves intersecting 

 the posterior margins at lar^o angles not far from flic genal extremities. 



IK > rtgflM Meek and W<.rth-n. An i-ritir.- individual, with c.'phalon iuclln 



Thorax compiled of ei^ht hroad, flat segments. Longitudinal lobation very 



> \er.v l.road. covering three-fourths of the entire width of the thorax. 



The segments are broad in the middle, narrowing somewhat at the axial furrows; 



on the pleura- they are very narrow, not grooved, and the beveled articulating 



planes extend for the entire distance from the dorsal furrows. 



Ps-idimn comparatively >hort, snl.semicircular on the margins. Surface 

 -month, sloping equally to the sides and posterior extremity, slightly concave just 

 within the, margin; wit hout external evidence of lobation or segmentation. On the 

 cast of the inner surface the axis is seen to be considerably narrower at the anterior 

 margin than at the termination of the thorax, and its lateral margins taper regularly 

 to a point not distant from the posterior extremity of the shield; in a favorable 

 light eight animations may be counted on the axis and five on the pleura-. The 

 articulating ring and groove on the anterior margin are broad and conspicuous. 

 l>oul.lnre broad, coarsely striated as in Isotelus. Surface ornamented, especially on 

 the extremital portion-, l.y coarse venation traversing the test transversely. 



;ry young entire example has a length of 1C. mm.; the largest extended 

 specimen i- -Jf, mm. in length, and the largest enrolled example 50 mm. in length. 



evident from certain isolated py^'idia that, th. limeii-ions were frequently 



exceeded. 



.-.i/iff. -Lower Tr.-r>t<.ri MiUrk Mirm-ai,.. t,a shales, WyknlT. 



1 -ciea was .-ri K lnal!y d-s,-ril--,l from it,,- I; fauna of 



Carroll anil K. 



' : '-' '" 'u* trentoneiuu. with which Ills 



>.y tl,.-i-,.ltlnt, ,,r '.,rrn.,f th.-farlal 



ihallownw- imdth of tbe thoracic Mgo lifr.nn*. 



,/thr.f th.-ir -y.-s. Th!> fralur,- i, -. 

 Dalman. th.- typ,?.,f r, M Al> , ln th( . Ihr ,.,. SJ 



; 'P- - v - '<<</'". -V. -. Th \,,,\n. siil.i . 



" of DJ al Immaturity, whi--h 



Dlmloutlon In . .. ( n hlitht t th- .-y,-s. a-. HI .V. ,,',/, -edly 



tbe a. 



rcreoce of thU foMll; tboogfa II ucful a* 



Indicating the JIlTorent staw rfonM. 



Pkletnolc FoMll*. v.,1. r II. IMS, pp. 



