THE FOSSIL STALK-EYED CRUSTACEA 81 



Genus MURSIA Leach 



Mtirsia Leach, in Desmarest, Diet. Sci. Nat., voL 28, 1823, p. 231; type, 

 M. cristata Latreille (Recent). 

 Carapace very convex, transversely oval, a strong spine at lateral 

 angle; front narrow. Chelipeds large, when folded fitting close to 

 body; hands large, compressed, distally widened, a superior laminate 

 and dentate crest, and a strong longitudinal ridge near lower edge 

 of outer surface. 

 Oligocene; Recent. 



MURSIA YAQUINENSIS, new species 

 Plate 19, figs. 3-5 



Description. — Surface of carapace (pi. 19, fig. 5) covered with 

 fine granules which vary in size and prominence; those of the pos- 

 terior half are finer than those of the antero-lateral half; those on 

 the tubercles are large and more crowded than elsewhere. The 

 branchial region is crossed by three blunt, oblique ridges; the inner 

 ridge is nearly longitudinal and bears three tubercles, the distance 

 between the second and third (posterior) being one and a half times 

 that between the lateral spine (missing in the holotype) and is 

 directed forward at an angle of about 45 degrees to the median line ; 

 it is furnished with two tubercles; the outer ridge is very faint, 

 nearly transverse and also bears two tubercles. Twelve small 

 antero-lateral teeth are indicated, only one of which approaches com- 

 pleteness; they are connected by a single rov/ of marginal gran- 

 ules, three or four granules in each interval; the teeth nearest the 

 orbit are smaller than the others. A raised rim of crowded bead 

 granules marks the postero-lateral margin. A portion of the ven- 

 tral surface bordering the lateral margin is preserved (pi. 19, fig. 3) : 

 it is coarsely granulate, the granules spaced and directed outward; 

 this area is separated from the smooth pterj^gostomian region by a 

 narrow, raised band of smaller and closer granules separated by 

 minute punctae which probably served as sockets for hairs. 



The sternum is represented by portions of three segments of the 

 right side, that at the base of the cheliped bearing the strong, curved, 

 downward pointing spine (pi. 19, fig. 4) which characterizes the 

 male; this segment is finely granulate except on and behind the 

 spine where it is coarsely so; the coarse granules are continued on 

 the next segment, except the inner half Avhich was covered by the 

 abdomen and is smooth; only the inner or smooth half of the next 

 segment is visible. 



Alongside the carapace there is a fragmei\t of the proximal end 

 of the merus of the posterior leg; it is granulate on the upper sur- 



