,i.i 



one-fourth the width of the thorax at any point The segments are slender 

 and distinctly ^romc'l for their entire length or within a very short distance of 

 their extremitie-. Tin- lir-t five segments appear to be obtusely rounded at 

 their termination-. Imt the last seven are acute. The sixth segment, though no 

 broader than the rest within the articulating lines, is greatly expanded at the 

 line of geniculation and each extremity is produced as a stout spine, consider- 

 ably beyond the termination of the py^idium ; these curve outward at first, 

 thence recurve and approach each other. Though their entire length is not 

 preserved, they could not have been less than 20 mm. long. The last six segments 

 are like the tirst live, except that they are curved more abruptly backward, their 

 terminations being acute. 



idium short, narrow in front, all the annulations being curved abruptly 

 backward. Anterior diameter 7.5 mm.; length 9 mm. The articulating ring of the 

 axis is very large and conspicuous; behind it is a single annulation extending entirely 

 across the axis, three others which extend from the dorsal furrows partly across, 

 these being followed by five or six rings which do not reach the dorsal furrows and 

 an- -evirated medially l>y a flattened area. like that in Kit'-riimrii-. The axis end- 

 .H-utely and does not reach the extremity of the pygidium. 



Kach of the pleura bears four or five ribs, the first of which is quite narrow, and 

 in, probably, the anterior moiety of the second, as it does not reach the margin. 

 There may also be seen a trace of a similar intercalary rib between the second and 

 third ribs. The second, third, fourth and fifth ribs end in acute, free points which 







were directed outwardly. 



Surface finely tubercled, the tubercles being coarsest on the border of the 

 cephalon and the ribs of the pygidium. The surface of the free cheeks was slightly 

 pitted or punctated. 



Formation and locality. Galena II me* tone (V), Plllmnre county, Minnesota (Museum No. 8436). This 

 specimen was found loose, and Its exact geological position K hence, uncertain. 



Ot*ervation*Thl* Is the moat completely known spectra of Cybel- from the American fauna*, 

 indeed the only species of the genus observed here except that iinur.-.l (.-. lillllnics under the namefn- 

 rrinuru* mint*, from the Quebec ,-P.II|. '. Newfoundland;* and of all the forms of this irenus that hare 

 been Illustrated no speclm. n -:,.* I..-U.T the general form .in 1 relation of the parts. 



Ctfbele is an eminently low.-r Silurian k'enuit, attaining Its maximum development and variat 

 form In the Scandinavian and Haltlc Silurian districts, at an horizon equivalent to that of C.ielnehrlli. 

 Tli-- unfortunate condition of the tflabella of mir -|i.'.-.m--ii precludes a UrirmiKhly reliable comparison 

 with othi-r forms; Imt the ch . ::utu, with short fnt- lTiiiinalioii> of Die ribs, SUneaU a 



specli > -hip with c. reraleiui* Shmhli,' from the tageC,, a somewhat earlier stage of Ihe - i 



ton |H ri.nl than that represvnl4-<l by th<> Oali-n;i llm<-tonr. None of the Russian speclM posMM the 

 cheek spines of C. 



POMIU. vol. I. p.M. ..', IMS. Thenproi.-. w. fnundrd no > (llx>lla. wl.lrh I. uplclnul v I,. 

 ; the pjrfldlum. bowerer. %Moclkted with It In n.. lllutrUmi , the teKriptlOB. l probably thai of m 



tlU-.UlooiJero.lU.lt. lur. TrilobltM. Ablh. I. p. JOJ. pi . xm. Be : pi. xr. Sf. 6 un.M. 



