REPORT OF THE STATE PALEONTOLOGIST 1902 1097 



length, but becomes concave posteriorly, forming a shallow 

 groove at the abrupt end. The terminal angles are noticeably 

 truncated. The appendage carried by the second sternite is par- 

 tially covered by that of the operculum [pi. 14, fig. 2]. It 

 is very slender, its greatest breadth not exceeding one sixth the 

 length [pi. 26, fig. 3 ; 13, fig. 4] . The anterior half is sublanceolate 

 with a triangular base; the posterior is attenuate and termi- 

 nates just within the end of the cleft. In the male the ap- 

 pendage is simpler and confined to the operculum, the follow- 

 ing sternite being entire [pi. 13, fig. 3]. It is wider and some- 

 what shorter than that of the female, the average length being 

 only about two and one half times the breadth. It is convex, 

 broadly lanceolate and slightly produced at the posterior free 

 end which just clears the edge of the operculum. A specimen, 

 in which a portion of this organ is scaled away [pi. 14, fig. 1] 

 gives a cast of the interior showing small elevated lines radiat- 

 ing from near the center backward, and may possibly represent 

 part of the vascular, or duct system of this organ. The two 

 sexes are about equally represented in numbers. 



The whole surface of the body is covered with imbricating, 

 crescentlike or angular scales, sometimes carrying smaller 

 ones of the same pattern. These scales are so minute on 

 certain areas as to appear almost obsolete. They are most con- 

 spicuous on the ventral side of the preabdomen and appendages. 

 On the cephalothorax and abdomen the scales point backward, 

 on the paired appendages toward the distal end, and on the 

 epistoma, forward. 



Hughmilleria socialis var. robusta var. nov. 



Plate 21, fig. 1, 2 



What appears to have been a varietal form of Hughmil- 

 leria socialis is represented by a nearly entire abdomen, 

 two first ring segments and an imperfect metastoma. 



The features which distinguish this form are : its larger size ; 

 proportionately much greater breadth; the greater convexity 

 of the dorsal posterior edge of the first ring segment and, in 

 some cases, the division of this edge into two, broad, smooth 

 lobes; the more noticeable contraction of the abdomen at the 



