234 S. H. SCUDDER ON THE FOSSIL 



The specimens vary in length from 18 ""• to 38 """■, and in breadth 1.5 """• in mi- 

 nute, probably "young, specimens to 5.5 ""■ in very large ones; usually they are about 

 3.5 ™™' broad. The segments are a httle more convex than in IK. sigillarice Daws., and 

 (with one exception, where the segments vary from .165 ™"- to .175 °"°- in length, 

 and the body is only 1.5 °"°- broad) vary in length from .55 ""• to 1.3 °™-, where 

 the body ranges from 2.5"'"- to 5.5 °™' in breadth ; the average length of the segment 

 to its breadth is as 1 : 5.574. The segments are ordinarily smooth, but sometimes appear 

 to be coarsely, u-regularly and very faintly scabrous ; they are but shghtly, if at all, in- 

 crassated at the anterior and posterior margms. 



The frustra are quadrangidar in shape, cross the segments regularly and are generally a 

 little less than twice as long as broad ; except in the case of the small specimen already al- 

 luded to (where they are .087 '^- in breadth), they vary from .275 """■ to .75 '"'"■ in 

 breadth ; in segments, the lengths of which vary from .55 "™' to 1.3 °™- the frustra 

 average .55 °"°- in breadth, and the breadth is to the length as 1 : 1.9. As in X. sigillarice 

 Daws., they are flat, except as they partake of the convexity of the segments, and then- 

 upper edges are slightly prominent. 



Besides the cross lines upon the segments, indicating the division of the frustra, finer, 

 fainter, parallel and more frequent impressed lines are occasionally seen ; some which were 

 measured were .0125 ™'°' broad, and on an average 1 "™- apart. In one specimen I 

 found a whitish substance, which appears to be the altered chitinous coat of the animal, 

 and in this were alternating elevations and depressions crossing the segment, at distances 

 varying from .1 ™™' to .175 °™' apart; they are in direct coutmuation of the fine lines 

 mentioned above, which at this point vary similarly in distance ; they differ, however, in 

 that the first mentioned lines are sharply defined furrows, separated by broad plane sur- 

 faces, while these are duU grooves between alternating slopes of elevation ; in the latter 

 also, the lines of depression are deepened and broadened at regular intervals, giving the 

 whole field a maculate, pitted appearance, apparently found in other chitinous spots, which 

 bear no trace of the lines ; it may be noticed that these various sculpturings usuaUy occur 

 on segments near the head and on the lower half of the body. 



I have not foinid any trace of foramina, nor are any legs visible, with the exception, in 

 a single instance, of what seems to be a basal joint ; it is .175 """• broad, or much 

 larger than in X. sigillarim Daws. In one specimen, in exactly the place where the eyes 

 should be, an aggregation of minute tubercles may be seen, arranged in five parallel rows, 

 each row containing from two to five tubercles ; very probably these are only accidental 

 roughnesses on the stone. 



Xylobius fractus sp. nov. 



I have seen but three fragments of this gaUy-worm, and my knowledge of its structure 

 is correspondingly limited ; only one fragment shows Avhat may be an anterior or a poste- 

 rior end, or both, and it is so imperfectly preserved that one cannot be sure whether 

 the lessening breadth of the extremities is real or accidental. The largest specimen — 

 and this is parted in such a way that it may have belonged to two individuals — is slightly 

 •curved in position, 25 °""' long, and composed of forty-five rings, the longer portion 

 counting twenty-eight ; another fragment, 7 ™"' in length, is composed of sixteen seg- 



