176 S. H. SCUDDER ON SPIXED MYRIAPODS 



other fossils, .and for which I scarcely understand how to account ; it is as if a cast of the 

 creature had been taken, left connected at one edge, then turned over on this edge as by a 

 hinge, without rupture, and laid clown beside it ; for here, and always, if I rightly recollect, 

 it is concave while the fossil proper is convex. But here at least it does not perfectly 

 repeat the parts which lie beside it, especially in that portion of it which I have had 

 drawn, and which is on the half of the stone on which the fossil lies in relief; for the 

 structure of the surface is quite different, and is uniformly flat (excepting for the general 

 concave curve of the whole) instead of showing the irregularities of the bosses on which 

 the spines rest, noticeable in the fossil itself; this surface is finely and regularly striate in 

 a transverse sense, a feature which no doubt belongs to the surface of the fossil at this point, 

 since it is found elsewhere, but which does not appear here on the specimen proper. This 

 fine transverse striation of the surface is a marked feature of this species, and seems to 

 be confined to the dorsal plates, although in the portion of which we have just spoken it 

 extends over a great breadth, apparently as great as the entire supposed width of the 

 dorsal plates, instead of being limited to the narrow breadth of the portion truly exposed 

 at their side. The fine striation seen over the lower half of the body apically is either 

 adventitious or it belongs to some similar cast as this puzzling duplicate ; it lies beneath the 

 body in a different axis, for the lines are oblique to the true plates of the fossil, whether 

 dorsal or ventral, and extend slightly beyond their actual limit. 



No spines are preserved, but their position can be determined to be the same as in other 

 species by the bosses which mark the bases of the upper series, and in a few places by the 

 small pits which mark the casts of the underlying spines of the lower series, seen through 

 the segments above. Neither can the legs be made out, but only faint indications of them 

 here and there of no value. 



There is however an additional though problematical feature in this fossil, of much 

 interest. Below the sixth segment behind the head, but still at some distance from it and 

 therefore not necessarily connected with it, is the impression of a long and slender, straight, 

 rod-like body, consisting of a close series of delicate transverse impressed lines, cut by a 

 central longitudinal impressed line ; it is half as long again as the width of the exposed 

 dorsal plates at this point, and nearly or quite as slender as the legs must be. Taken by 

 itself, it would appear of little importance, detached as it is from the body ; but considered, 

 with somewhat similar instances in other species of a long and straight appendage to seg- 

 ments at about this point, it cannot be denied that it may indicate an intromittent male 

 organ at this point. 



The length of the body, if uncoiled, would be about 44 mm. ; its extreme width 4.5 mm. ; 

 its width next the head 1.75 mm. ; and its width at the seventh segment from the tail 3.8 

 mm. ; the length of the dorsal plates in the middle of the body is 2.1 mm. ; the length of 

 the problematical rod 3.2 mm. The specimen comes from the Mazon Creek nodules, and 

 was sent me for study by Mr. J. W. Pike. 



Eiqihoberia fiabellata differs strikingly from the other species described in the form of 

 the terminal segments, as well as in the comparative stoutness of the entire body, and its 

 unusually tapering anterior extremity and small head. The spines being unknown and no 

 clear indications of the legs preserved, these important features necessary to distinguish a 

 creature of this sort are much to be desired, but the further distinction of a transversely 



