428 SAMUEL H. SCUDDER ON NEW 



are remarkable for their coarse sculpture, inequnlit}' of the subsegments, and general form 

 of the segments, although some at least of them have spines which differ somewhat from 

 those of the previous specunens, perhaps due, hovrever, to their belonging to different 

 longitudinal series. 



One of them which is here figured (fig. 6) sho ws only about a dozen or fifteen seg- 

 ments from near the anterior end of the body, and is considerably larger than the largest 

 specimens hitherto known. It is preserved upon the side and the spines seen at one 

 edge are evidently those of the subdorsal series. The segments are about three times 

 as broad as long, but the flattening of the body largely conceals the evident previous in- 

 equality of the subsegments; the surface is very coarsely granular (fig. 5). The spines 

 ai-e rather stout, very much shorter than the segments, curved backward, and show no 

 sign of any anterior fine basal spinule, but instead a distant basal posteiior spinule of 

 similar coarseness as the main spine, but very low; these are not well shown on the plate 

 as they can only be well made out by shifting the point of view. The legs are slender 

 and nearly as long as the width of the body. The ventral plates are seen in part and 

 are normal. 



Length of fragment, 58 mm. ; breadth, 10 mm. 



The specimen comes fromMazon Creek, 111., and was received from Mr. R. D. Lacoe, 

 in whose collection it bears the number 1805 ij. 



Another specimen, also received from Mr. Lacoe and l^earing the number 1805mn, 

 is of nearly equal size, preserved in a sinuate curve, lying upon its side, and showing 

 similar parts; it is much more complete, showing almost the entire length of the animal, 

 the head possibly and a portion of the tail certainly absent. About thirty-eight seg- 

 ments are present. It is of nearly uniform size throughout, except that it is slightly 

 larger over a rather broad space in the middle, the front third about equal, and the pos- 

 terior part considerably smaller, giving a contour unlike any before met with. The 

 segments have the usual proportions and distinct heavy sculpture of the species, the 

 granulations, however, somewhat exceptionally unequal and distant. Here also the spines 

 of the subdorsal series are much as in the specimen last described, but do not show so 

 clearly the posterior basal spinule, and also show no sign of any anterior one. The legs 

 are slender, extended at full length, and evidently longer than the width of the body in 

 advance of the widest part. 



Length of fragment if extended, 95 mm.; greatest width, 9.5 mm. 



Two other specimens also received from Mr. Lacoe, Nos. ISOokl and 1805h, of smaller 

 size, also belong here; they show nothing peculiar excepting that each at its hhider ex- 

 tremity, which in one case is perfect, shows that the subdorsal spines at this extremity 

 of the body were apparently simple but remarkably stout, shoi't, and blunt; they are only 

 twice as high as their basal breadth. 



To this species I also refer doubtfully a specimen from Mazon Creek (fig. 2) sent 

 me by Mr. Gurley, showing about twenty-four segments preserved on a side view with 

 some of the legs. No spines are present and only a few places are at all characteristic. 

 It is in any case a small specimen, measuring but 40 mm. in length, and 1.75 mm. in 

 diameter. It is nearly equal throughout, tapering only a little toward the tail. The legs 

 are 2 nnn. long. 



