158 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



and T. W. Vaughan, collectors. 1911. Station 6020a. Cat. No.. 

 324238, U.S.N.M. 



Measurements (approx.). — Length of carapace (spines excluded), 

 14 mm.; width (spines excluded), 14.4 mm. 



Holotype. — Species represented by one specimen showing part of 

 the carapace and no appendages, enclosed in a nodule which has been 

 broken in two. Nodule not. much larger around than the carapace. 



Carapace nearly as long as wide, spines excluded; width between 

 outer angles of orbits a little greater than posterior margin. Chord 

 of the antero-lateral margin nearly twice as long as that of the 

 postero-lateral margin. Antero-lateral' margin divided into 2 parts, 

 the anterior two-fifths being slightly convex, the posterior three- 

 fifths very convex with a tubercle at its middle. Postero-lateral mar- 

 gin somewhat sinuous, but in general concave; posterior margin 

 slightly convex, about twice as long as the slender spine at either end 

 which is directed backward and slightly outward. Lateral spine also 

 slender, but longer, half as long as the postero-lateral margin and 

 pointing obliquely backward. 



The central and anterior part of the surface of the carapace is 

 lacking. There are, however, two oblique, parallel, branchial fur- 

 rows ; between them a row of 3 tubercles and some scattered granules ; 

 the outer part of the branchial region is higher and rough with 

 irregular tubercles which are more or less confluent. Cardiac region 

 high, with a median tubercle on its posterior slope; in almost the 

 same plane transversely, but on a lower level, there is another tubercle 

 on each side just above the postero-lateral margin. 



There is a very small hollow in the nodule where the point of the 

 front rested, and on the other half of the nodule may be seen the 

 lower surface of the front where it j oined the interantennular septum. 



The orbits are small, their upper and lower margins formed by 

 two teeth, the innermost advanced, separated by a blunt V-shaped 

 sinus. 



On the lower surface, the inner tooth of the orbit is considerably 

 elevated (that is, ventrally). A sharp ridge runs obliquely back- 

 ward from or near the epistome, and is armed with a tooth at its 

 posterior third. 



MURSIA MACDONALDI, new species. 



Plate 58, fig. 21. 



Type-locality.— Panama Canal Zone. Las Cascadas section. Fifth 

 or topmost limestone. Emperador limestone. Oligocene series. D. 

 If. MacDonald and T. W. Vaughan, collectors. 1911. One specimen, 

 part of left cheliped. Station 6019,?. Cat. No. 324229, U.S.N.M. 



