6CU0DER.J CANADIAN FOSSIL INSECTS. 61 



titute of armature, the anterior and posterior margins a little elevated, 

 and the body of the segment between them gently concave. The species 

 does not appear to have been flattened to so great a degree as the preceding, 

 and from the preservation of some of the fragments evidently tapered 

 toward the hinder extremity. In the preceding, no specimens indicated 

 any tapering, though not enough of them were preserved to say that they 

 did not taper. The hinder extremity being preserved in one specimen 

 here, it is seen to be bluntly rounded. The largest number of contiguous 

 segments in any preserved fragment is 37. 



Like the preceding, these specimens all come from the sigillarian 

 stumps of Nova Scotia, and are due to the researches of Sir William 

 Dawson. It has seemed fitting to dedicate the species to one who with 

 liim first made the discovery of this imprisoned fauna of the fossil trees. 



Xylobiiis sig'illariai Dawson. 



A couple of imperfect fragments are referred here, but add nothing 

 whatever to what was before known. 



Xylobius simllis Scudder. 



PI. v., figs. 1, 2. 



Five specimens ()f a Xylobius larger than the others, of which the best 

 preserved fragment is figured on the plate, are referred to the largest of 

 the species previously described, with which they agree fairly well in 

 structure. As none of them shows more than a portion of the animal, 

 they add nothing to our knowledge of its form. The segments are not 

 very convex, and in the specimens seen vary from a little less to a little 

 more than five times as broad as long, and have a length of a little more 

 than a millimetre ; the frustra are generally somewhat longer than broad, 

 but in the three segments shown in fig. 1 (which represents, still further 

 enlarged, three segments from just to the left of the middle of fig. 2) 

 they are but very little longer, though the figure somewhat exaggerates 

 the similarity of the dimensions. 



Xylobius fractiis Scudder. 



Three specimens are referred here, but with much doubt ; they con- 

 sist in each case of only a very few and imperfect adjoining segments. 



Xylobius dawsoni Scudder. 

 PI. v., fig. 3. 



Seven specimens are referred to this species, but they consist in all 

 cases of only a few contiguous segments. The longest is shown in fig. 3, 



