NOTES ON PALEOZOIC CRUSTACEA NO. 4.— ON A 

 NEW TRILOBITE FROM ARKANSAS LOWER 

 COAL MEASURES. 



BY A. W. VOGDES. 



Griffithides ornata sp. nov. 



The only specimen of this new species was 

 discovered in Conway county, Arkansas, and 

 consists of a head shield which is unfortunately 

 not quite perfect, only exhibiting the right side 

 and part of the glabella, with portions of the 

 thorax and an entire pygidium ; but it shows 

 "^'omata'"" sufficicnt ncw characters to authorize us in con- 

 sidering it as a new species. 



The head shows that the latero- posterior angles 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 axal 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 center 

 of each ring. The pleura? are smooth, each plural groove 

 extending slightly beyond the fulcral point; the extrem- 

 ities are probably rounded, but this is not indicated by 

 the imperfect specimen now before us. 



The pygidium 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 



2d Ser., Vol. IV. April 8, 1895. 



