smith. J ^i^ [Oct. 2, 



" The head shows that the latero-posterior augles are produced into 

 short spines extending to about the third segment of the thorax, the 

 glabella is pyriform, gibbous in front, and destitute of lateral furrows ; 

 basal lobes prominent The posterior border of the glabella has two 

 small, round nodes. The cervical lobe is broad and well marked, much 

 broader than the axial lobes. 



"The thorax exhibits imperfectly parts of the pleura' and also the axis. 

 Thorax with nine segments. The axis shows a series of nodes running 

 through the centre of each ring. The pleurae are smooth, each pleural 

 groove extending slightly beyond the fulcral point ; the extremities are 

 probably rounded, but this is not indicated by the imperfect specimen 

 now before us. 



"Thepygidium exhibits both in the axis and lateral lobes distinct 

 segmentation. The axis does not extend to the posterior margin. The 

 entire pygidium is surrounded by a marginal border, which widens out 

 slightly anteriorly. 



"The tail is parabolic in form, very convex and not as broad as the 

 head, measuring on its anterior border 12 mm. The axis is broad, con- 

 ical and prominent, occupying a little less than one-third the width of 

 the tail on the anterior margin. It is marked with eleven rings ; these 

 become smaller and smaller and end in an obtuse point. Each ring is 

 distinctly ornamented along the centre by a series of nodes, arranged 

 into three double rows of two each. The sides of the axis are smooth. 



" The lateral lobes are slightly flattened on top to the fulcral point. 

 They are marked with seven pleurae ; the grooves between the pleurse 

 are deep and distinct, each being rounded on top and ornamented with 

 a single node at the fulcral point; here they bend suddenly and join 

 the marginal border. 



''Locality and Position.— hovi-er Coal Measures, T. 5 N., R. 16 W., 

 section 17, near centre of northwest quarter of the section, Conway 

 county, Arkansas. From the collection of the Geological Survey of 

 Arkansas. 



"Affinities and Differences. — This species in some of its features resem- 

 bles Phillipsia rcemeri WoWer (Ueber die Trilobiten Steinkohlenformatioti 

 des Ural, PI. ii. Fig. 17), especially in the markings of the tail, which 

 shows seven pleunt ornamented by a single node at the fulcral joint, 

 but it difters in form and especially in the marking of tlie axial lobe, so 

 much so that it could not be placed under ]VI611er's species. There is 

 also a resemblance of this species with Phillipsia {Griffithides) scitula 

 Meek and Worthen, from the Illinois Coal Measures. It has the same 

 number of rings in the axis of the tail, and the same characteristic 

 pleurae and ornamentation, but the Arkansas species difters greatly in 

 size and also in the number of pleurae, seven instead of six. The axis 

 is not as wide as in Griffithides scitula and not distinctly flattened on 

 each side. The limb, although moderately wide and smooth, is not 

 depressed or nearly flat, but convex. Secondly, the ornunicntation of 



