16-i Cincinnati Society of Natural History. 



tinued over the sternal arch, and also a flattened and excavated longi- 

 tudinal process, which extends forward over the sterna of the somites 

 immediately in front. Somites of the post-abdomen short, with artic- 

 ular surfaces allowing great freedom of motion. Head and lateral ap- 

 pendages unknown. 



This genus is characterized by the extraordinary development of the 

 epimeral and episternal elements of the thoracic somites, by the ver- 

 tical median processes on the ventral side of the last segments of the 

 post-abdomen, the large anchor-like process preceding them, and by 

 the alternate anchylosis and sutural separation of the thoracic sternal 

 and tergal elements. 



While the removal of this fossil from the Cysticlea to the Crustacea, 

 under a new class and genus, would be found a sufficient excuse by 

 many writers, under cover of which to plunder this eminent author of 

 his species, I shall retain his expressive name, and leave the species 

 to his credit. 



Enoploura balanoides, Meek. 



Body concave ventrally, convex dorsally, and composed of somites 

 divided into dorsal, lateral and ventral regions, by well-defined sutures. 

 Surface irregularly granulose. Sternum of posterior segment of the 

 thorax divided mesially, widened and excavated posteriorly, nar- 

 rowed in front. Episterna largel}^ developed, the lower part meeting 

 the sternum, the upper flexed^ nearly at right angles, and meeting 

 the epimera. Epimera widened behind, slightly excavated on the 

 interior angle, narrowed in front, and extending to the central 

 lateral angle of the heptagonal tergum, where they join the epimera of 

 the next somite. Tergum heptagonal, convex above, slightl}' carinate 

 on the median line, somewhat excavated posteriorly. Sternum of next 

 somite mesially anchylosed. Episterna as before, but more developed 

 ventrally. Epimera trapezoidal, widest in the middle, and tapering to 

 a point in front, which lies in the angle formed by the outer edge of 

 the tergum and the inner edge of the episternum. Tergum not mesial- 

 ly anch^dosed, narrowed behind, widened before, the anterior extremi- 

 ty being lost in all the specimens. Post abdomen made up of fourteen 

 distinct, short, loosely articulated somites, the first eight of which bear 

 no appendages; ninth bearing a large transverse process, arising at the 

 epimeral suture of either side, and bending forward so as to look to- 

 ward the head of the animal; from the base of this process springs a 

 longitudinal one, extending forward and ovei'l3dng the sternal region 

 of the somites immediately in front, which are somewhat crowded for- 

 wai'd and flexed to receive it. The remaining somites bear longitud- 



