420 SAMUEL H. SCUDDER ON NEW 



sometimes furnished Avith tubercles. Much remains to be learned of the structure of all 

 the animals here brought together. 



EiLETicus Scudder. 

 As already remarked, the discovery of better remains proves that this genus finds its 

 place better here than in the Archipolypoda. The imperfection of the only specimen 

 known when this genus was founded led to several errors of interpretation which may 

 now be corrected. The head was not composed, properly speaking, of a single apparent 

 segment, but of two, a lai'ger anterior and smallei* posterior segment, each with its inde- 

 pendent vaulting, the hinder with a pair of foot jaws arising from its posterior portion; 

 but the two segments are not separated as in modern chilopods by a distinct suture, but 

 only by a broad and shallow transverse sulcus from the meeting of the two arches. 

 Nor do any of the segments bear, as was judged from the appearance of the non-attached 

 anterior members of the original specimen, moi-e than a single pair of legs, but very little 

 can be said about them. The form of the segments and their tuberculation would appear 

 to be subject to some variation. 'No complete specimens have been found, nor any in 

 which more than thirteen or fourteen segments behind the head are preserved. 



Eileticus anthracinus. 

 PI. 38, fig. 5. 



Eileticus antJiracinus Scudd., Mem. Bost. Soc. Nat. Hist., in, 179 (1882). 



Another specimen of this species, far more pei'fect than the first and with its reverse, 

 has been found at Mazon Creek, and sent me by Mr. Lacoe, in whose collection it bears 

 the number 1835ab. It exhibits the dorsal surface of the anterior extremity, very likely 

 about half the body, but fragmentary and without appendages, of an animal of about the 

 same size as the original. It shows about thirteen segments besides the head. The lat- 

 ter, broken in front, shows a flattened globulai- mass of smooth texture, with a faint trans- 

 verse median impression separating independently though'faintly arched anterior and poste- 

 rior portions; a longitiidinal median impression of similar depth crosses both but is not 

 accompanied by an indejiendent arching of the head in the other sense; from the middle 

 of the posterior margin of either lateral half of the hinder section of the head arises a de- 

 cided, cornuoixs, tapering, forwai'd and downward reaching, independent arched member, 

 plainly representing the foot-jaws. 



The segments of the body are sub-equal in length, but enlarge in breadth in passing 

 from the first behind the head where it is slightly narrower than the head to about the 

 sixth segment, beyond which they are about equal; each, when perfectly preserved, shows 

 a transverse, marginal, strong and abrupt, rounded sulcation at its anterior edge, the mar- 

 gins of wliich are prominent, and the hinder at a much higher level than the anterior or 

 proper margin of the segment. The surface of the segment is smooth and uniform, ex- 

 cept that at the extreme lateral margins, as in the oi'iginal specimen, are seen more or 

 less distinctly small tubercular bosses serially arranged. The best preserved segments 

 appear to be a little more than twice as wide as long. 



