176 PROCEEDINGS OP THE ACADEMY OF [1880. 



DESCRIPTION OF A NEW CRUSTACEAN FROM THE UPPER SILURIAN OF 

 GEORGIA, WITH REMARKS UPON CALYMENE CLINTONI. 



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



Calymene rostrata Vogdes. 



This species differs in one aspect from the usual forms classed 

 under the genus Calymene^ in having a projecting process arising 

 directly from the cephalic shield in front of the glabella, and in 

 this respect resembles Homalonotus rhinotrojns of Angelin, a 

 species which has been referred by Salter, in his monograph of 

 British Trilobites, to H. Knightii. Salter says "the front margin 

 ^'a- 1- is of most singular structure and may be 



described as tricuspid. The narrow edge 

 is so deeply indented, and at the same time 

 folded, that the front portion overhangs 

 the rostral shield, forms one projecting 

 angle flanked by two smaller projections 



Calymene rostrata Vogdes. 



The glabella and fixed cheeks Opposite the axial furrows, exactly like the 



showing the projecting pro- ,. , , , . , « r. ^. 



cess. salient and re-entering angles of a forti- 



fication." Our species has only the central triangular projection, 

 the margins of which are deflected, and the marginal border unites 

 and forms a triangular projection, directly in front and on the 

 median line. 



The following characteristics are drawn from three specimens, 

 consisting of the glabella and fixed cheeks, and many p^-gidia 

 found associated with them at the same locality. 



The glabella is convex and widens out posteriorly, being- 

 contracted in front ; the sides are marked with three lobes, 

 the basal one large, the middle lobe nearly spherical, the third 

 is somewhat obscurely defined. The fixed cheeks are separated 

 from the glabella by deep dorsal furrows, but opposite the eyes 

 the furrows are restricted hy a buttress thrown across it, nearly 

 touching the middle side lobes ; the cheeks are gibbous but 

 not elevated above the glabella, they are narrow along the 

 sides of the glabella and widen out laterally from the eyes. 

 The facial sutures cut the posterior angles of the head, but 

 anteriorl}^ from the eyes these lines run almost straight with 

 a slight tendenc}- outward, and pass over the margin. The 

 neck furrow is continued nearly to the posterior angles of the 



