CAEBONIFEROUS MYRIAPODA OF ILLINOIS. 437 



four or five of them very well, — at least the dorsal scutes. These consist of simple 

 plates with well rounded lower edges which apparently extend beyond the lateral limits 

 of the body proper (to judge by the transverse curving I'idges generally seen above their 

 termination), about twice as broad as their greatest (superior) leugth, with indications 

 of some thickening of the anterior and posterior margins, preceded by a more or less dis- 

 tinct and extensive transverse furrow. No definite signs of the ventral scutes can be 

 seen and they are apparently covered by the presumed lateral expansion of the dorsal 

 sciites which on a side view would conceal them. The legs are seen in several places, 

 but too obscurely and intermingled to say more of them than that they appear to be cer- 

 tainly very stout and long and longitudinally ridged. Neither extremity of the body 

 is seen and there is no apparent sign of any tapering. 



Length of specimen if inicoiled, 43 mm.; length of single segments, 2.5 mm.; breadth 

 of same, 5.5 mm.; breadth of legs near middle, 0.75 mm. 



The specimen occurs in a nodule from Mazon Creek, 111., and was collected by Mr. J. 

 C Carr, to whom I owe the opportunity of studying it. It has since been secured by 

 Mr. Lacoe, in whose collection it bears the nmnber 1823ab. 



Here also I am inclined to place a similarly coiled but much smaller specimen (fig. 3) 

 from the same locality, preserved in a small nodule sent me by Mr. R. D. Lacoe and 

 bearing the number 1823cd. It is rather obscure and shows little more than the dor- 

 sal scutes seen on a side view with no sign of spines or legs or frustra. About forty- 

 two segments are represented and all are of nearly the same size and in their relative 

 proportions closely resemble the larger specimen before described. The texture of the 

 surfiice is very finely granular, almost smooth. If uncoiled, the ci'cature (imperfect) 

 would be about 36 mm. long; its width is 2.5 mm. 



Archiulus? sp. 



PI. 37, fig. 1. 



A species of myriapod apparently belonging to this genus but very obscurely preserved 

 on black shale amid a mass of vegetable debris, especially fern leaves, was sent me by 

 Ml'. E. D. Lacoe from the Maiden Mine, Kittanning coal, Kanawha Co., "W. Va., and 

 bears in his collection the number 1810a. It represents an openly coiled body, appar- 

 ently nearly complete as to length, about 85 mm. long, composed of from forty to fifty 

 segments very obscurely defined. The body is largest at what is taken to be the head 

 end, tapers rapidly to the head and very gradually to the tail end at the edge of the 

 stone. Generally speaking the segments are aboi;t twice or a little more than tAvice as 

 broad as long, and the surface is generally covered with an exceedingly delicate and 

 uniform striation transverse to the body, and in some places at the head end also lon- 

 gitudinally; although not detected elsewhei-e on the stone, it is suspected to be extraneous 

 to the fossil. 



Xylobius Dawson. 



This genus, peculiar for the frustrate dorsal scutes of the body, originally described 

 from the sigillarian stumps of Nova Scotia, is now somewhat Avidely known, occurring 



