92 Xorth American 



ruptly at tive-sixths of the whole length in an obtusely rounded apex. The 

 ribs on the axis are depressed convex, becoming smaller and more crowded 

 toward the apex, each with 8 or 9 tubercles, which are confined to the mid- 

 dle third of the width of the axis, and are situated near the posterior margin 

 of the ribs. The side lobes have 10 or 12 depressed convex ribs, the last 

 three indistinct, the first three or four with a very obscure fine groove near 

 the posterior edge, in the outer third of the length. The smooth border is 

 about one-fourth the width of the side-l.»bes at the anterior angles, but a 

 little wider behind ; all the space behind the apex of the axis is smooth. 

 Each rib has nine or ten small tubercles near its posterior margin. On the 

 posterior third of the pygidium there is an obscure shallow groove along the 

 inner edge of the smooth border." 



Length of the specimen. \2\ mm. ; width at the anterior margin, about 

 12 mm. 



Oeological posit'wn aiidlocalHy. — Lower Carboniferous, Kennetook, Xova 

 Scotia. 



There ai-e two forms of the geims PhiUipsin described by C;i- 

 riMdiaii palaeotitologists, from the Windsor Limestone of Nova 

 Scotia, which nppe;ir to be identical wirli Phillipsia Merameren- 

 sis, Sluimard. The first, PhiJUpsia Hoivi, Billings, was de- 

 scribed f]"om a pygidinm with 17 or 18 Mxial rings and 12 side 

 ribs in the text, bnt figured wnth 16 axial rings and 12 side ribs. 

 Can. Nat., Vol. VIII, p. 209. 



A com])arison of the second species from the Windsor lime- 

 stone (PhiUipsia Vindohonensis, Hartt.) shows no essential 

 ))oints of difference, except with regard to the nnmber of axial 

 rings in the second which are given as 12 from an imperfect 

 specimen, with two or more of the anterior segments wanting. 



PHILIilPSIA TUBERCUILATA, Meek and Worthen. 



PhiUipsia tuberculata, Meek and Worthen. 1870, Proc. Ac. Nat. Sci. Phila., 

 Vol. XX, p. 52. 

 Attaining a large size. Head and thorax unknown. Pygidium semi- 

 elliptic, the length being nearly three-quarters the breadth, very convex ; 

 posterior margin obtusely rounded ; lateral margin diverging rapidly for 

 ward, with convex outlines. Axial lobe well defined, obtuse, and rather 

 prominent behind and gradually widening forward, with nearly straight 

 sides ; rather distinctly more elevated than the lateral lobes, which it nearly 

 equals in breadth at the anterior end, as seen in a direct view from above, 

 but one-quarter narrower than the latter, measuring over the curve of each; 

 showing 16 or 17 straight, well defined segments, each of which is provided 

 with six small tubercles, arranged so as to form six rows. Lateral lobes 



