DESCRIPTION OF A NEW CRUSTACEAN FROM THE CLINTON GROUP 

 OF GEORGIA, WITH REMARKS UPON OTHERS. 



BY ANTHONY W. VoGDES, U. S. A. 



Encrinurus Ameriosnus, Vogdes (n. s.) 



Pjgidium elongated — triangular in form, strongly arched on 

 the anterior border and very convex, produced behind forming 

 a muronate extension. Length 10 mm., greatest width 8 mm., 

 or nearly f as wide as long. 



Axis narrowly elongated, flattened on the surface and sharply 

 pointed behind, marked by 20 or more axial rings ; the first 13 

 extend entirely across, the others appearing only as notches on 

 the sides, obscurely indicated in the specimens before us. The 

 axis has a central row of nodes, which appear on the 1, 6, 9 

 and 12 ring, and possibly on others. 



The lateral lobes are marked by six pairs of ribs, the anter- 

 ior three of which are distinct and free at their outer extremi- 

 ties, the other three being; united at their outer ends, the 

 posterior pair being parallel to and appearing almost as a part 

 of the axis. The ribs are abruptly directed backward, and dis- 

 tinctly separated from each other by rather deep grooves, they 

 gradually decrease in size as they approach the termination of 

 the pygidium, being rather flat on the surface. The first pair 

 originate almost opposite the first axial ring, the second be- 

 tween the 2 and 3, the third between the 5 and 6, the fourth 

 between the 7 and 8, the fifth pair run sub-parallel to the axis 

 and the sixth pair are only separated from it by a shallow 

 dorsal furrow. 



This species approaches Encrinurus elegantulus, Billings 

 (Catalogue Silurian Foss. Antico3ti, p. 62), in general form, 

 the axis of this species has 24 axial ring of which the first 8 or 

 9 extend entirely across it, the others being represented by 

 elongated pits on each side, but it lacks the nodes. The lateral 

 lobes of Encrinurus elegantulus are marked with five pair of 

 ribs, the first four being free at their extremities, the fifth pair 

 being slightly curved outwards, and conveging toAvards the axis 



