294 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 5J. 



Thorax with sixteen segments of the same character ; the body 

 of the thorax Hes well within the long genal spines, owing to the 

 shortness of the spinous extensions of the pleurae ; its sides are sub- 

 parallel back to the tenth segment, where they begin to arch inward 

 toward the small pygidium ; axial lobe convex, about the same width 

 as the pleural lobes, and narrowing gradually in width, a small 

 elongate, median node, with a base as long as the width of the seg- 

 ment, occurs on each segment, and there is a low, rounded elongate 

 tubercle on each side that is much like that on the axial segment of 

 Holmia kjcndfi [compare fig. 4, pi. 29, with fig. 7, pi. 27] : an 

 elongate, subtriangular tubercle next to the dorsal furrow on the 

 anterior side of the segment is also well shown by fig. 5 ; usually 

 the elongate tubercles of the axial lobe have disappeared by com- 

 pression of the test ; pleural lobes nearly flat from the dorsal furrow 

 out to their curved spinose extensions where they arch gently down- 

 ward ; each pleura has a broad, strong furrow that is broadest next 

 to the dorsal furrow from whence it narrows very gradually to 

 just within the curved terminal spinous extension of the pleurae. 

 The posterior margin of the spinous extension is arched forward 

 from the posterior margin of the pleurae, which gives a beaked or 

 slightly hooked outline to the termination of the pleurse. 



Pygidium small ; width at the anterior margin and length sub- 

 equal ; the sides extend slightly outward from the anterior margin 

 and terminate in short spines ; the posterior margin is slightly arched 

 backward at the center and inward on each side toward the base of 

 the postero-lateral spines ; axial lobes with one anterior transverse 

 ring that appears to bend backward along the outer margins and 

 extend into the terminal spines ; back of the transverse ring a sub- 

 triangular termination of the axial lobe, of equal width and length, 

 occupies the central area ; it does not reach the posterior margin, 

 and it has no traces of transverse rings or furrows ; with the possible 

 exception of the rounded outer marginal rim there are no indications 

 of pleural extensions of the rings across the smooth space between the 

 axial lobe and outer margins ; the anterior ring shown by fig. 1 1 is 

 the forward extension of the first ring that slipped beneath the ter- 

 minal segment of the thorax. 



Surface strongly granular on the outer rim of the cephalon [fig. 

 7] , finely granular over most of the test, and with irregular network 

 of fine elevated ridges that may give a pitted appearance in some 

 places [fig. 8] where the ridges are crowded, or an open pattern 

 with elongate meshes on the cheeks and segments. 



